Dont force ../.deps in third-party/CMakeLists.txt

- third-party is built under .deps by default instead of using its own
  ${CMAKE_BINARY_DIR}, move this default setting out of the cmake
  settings and into the Makefile.
- As a consequence the workflow of building third-party using CMake
  should feel more natural, avoid the additional folder or setting
  DEPS_DIR from the command line.
- This commit does not change the default behaviour when calling the
  Makefile wrapper.
Allow cmake caller to override DEPS_PREFIX

- Caller can override bundled dependency location using
  DEPS_PREFIX
- Cache variable DEPS_PREFIX, using .deps/usr by default
- Removed unused variables DEPS_BIN_DIR, DEPS_BUILD_DIR, DEPS_DIR
  DEPS_INSTALL_DIR
- Corner case: if the caller tries to override DEPS_PREFIX after a
  successful cmake configuration, the caller needs to clear the cache
  because dependency checks are based on the old value
build: include the flags for the build type in the _FORTIFY_SOURCE check

It turns out the check was being performed without optimizations enabled
even when the CMAKE_BUILD_TYPE was set to a release build.  This led to
_FORTIFY_SOURCE's level not being correctly determined, and us failing
to apply the correct workaround.

To counter this, we'll take the default flags for the build type and
apply them.  Also, if options are passed via CFLAGS, they are
automatically passed on to the underlying build.  So this should cover
all the necessary ground.

This fixes #1647.
coverity/13695: Unchecked return value: RI.

Problem    : Unchecked return value (CHECKED_RETURN) @ 8554.
Diagnostic : Real issue.
Rationale  : Other invocations of `do_source` are checked and generate
             an error message if fail. There seems to be no reason why
             this particular instance could not fail the same.
Resolution : Check invocation and generate error message on failure.
coverity/13696: Unchecked return value: RI.

Problem    : Unchecked return value (CHECKED_RETURN) @ 2644.
Diagnostic : Real issue.
Rationale  : Other `u_save` invocations are checked, and there's no
             reason to think this invocation could not fail.
Resolution : Check and return if failed (other previous checks in the
             same function just return, without reporting error, so
             we just do the same).
Passing-by: Fix FALSE/FAIL confusion.

FALSE was being used instead of FAIL.
They happen to have the same value, so it works the same.
But from function comment it's clear it uses the OK/FAIL convention.
coverity/75594: Explicit null dereferenced: RI.

Problem    : Exlicit null dereferenced (FORWARD NULL) @ 2859.
Diagnostic : Real issue.
Rationale  : Code within `if (!p_bk)` seems to assume `backup` not null
             at that point, which may not be true.
Resolution : Don't enter conditional on null `backup`.
Merge pull request #1688 from elmart/coverity-issues-1

coverity issues
Fix warnings: option.c: makeset()/put_setnum(): Various (3): FP.

Problems   : Dereference of null pointer @ 6251.
             Dereference of null pointer @ 6267.
             Dereference of null pointer @ 6351.
Diagnostic : False positive.
Rationale  : Problems occur if varp is null after
             `varp = get_varp_scope(p, opt_flags);`.
             That can only happen if option is hidden. Those are options
             that can be set (for backwards compatibility reasons) but
             that do nothing (see `:h hidden-options`,
             `:h missing-options`). In particular, even if setting them
             is allowed, value is not stored, so these options have no
             real value.
             So, suggested error paths should not occur, as checks
             comparing option value and default value should discard
             them.
Resolution : We could just `assert(varp)` before line 6235
             `varp_local = varp;`. That was tried and worked.
             But we prefer modifying the code to explicitly skip hidden
             options.
             A redundant `!istermoption(p)` is removed too (it's already
             checked by for loop condition).
Fix warnings: syntax.c: get_id_list(): Double free: FP.

Problem    : Double free @ 5213.
Diagnostic : False positive.
Rationale  : I haven't been able to find the real reason why this is
             signaled. Nonetheless, I've been able to track down the
             introduction of this warning to commit
             77135447e09903b45d1482da45869946212f7904.
             The change there affecting this function is just a
             transformation maintaining semantics. So, this must be a
             FP, though I can't explain why.
Resolution : Revert changes in mentioned commmit touching this function.
Fix warnings: window.c: win_close_othertab(): Np dereference: FP.

Problem    : Dereference of null pointer @ 1980.
Diagnostic : False positive.
Rationale  : I haven't been able to find the real reason why this is
             signaled. Nonetheless, I've been able to track down the
             introduction of this warning to commit
             77135447e09903b45d1482da45869946212f7904.
             The change there affecting this function is just a
             transformation maintaining semantics. So, this must be a
             FP, though I can't explain why.
             Analyzer thinks `win->w_buffer` can be null in line 1980,
             following an error path assuming win->w_buffer null at line
             1819. Given that `win_close` function was not modified by
             mentioned commit, I don't understand why this path is
             analyzed after the changes, but not before them. Or if it's
             analyzed, why it's discarded before changes but not after
             them. I don't see anything in changes to
             `close_last_window_tabpage` that should affect to
             being able to deduce `win->w_buffer` is not null.
Resolution : Assert buffer not null in `win_close_othertab`.
             Function comments state that passed window should have a
             buffer that can be hidden, which implies there should be a
             buffer.
             Reverting changes to `close_last_window_tabpage` in
             mentioned commit would be another way to fix this (tried
             and worked).
             But assert is preferred in this case because flat style
             reads better and we have some other way to fix it.
Use a local viminfo file when running the old tests.

This is required after defaulting to `nocp`, so that ~/.nviminfo
files don't interfere with the old legacy tests.
Merge pull request #1698 from elmart/clang-analysis-fixes-6

Fix clang analysis warnings. (6)
Remove superfluous settings from legacy tests.
Reimplement :drop (vim-patch:0)

The :drop ex command was inadvertently removed when removing FEAT_GUI.
This patch reintroduces it.
Detect and propagate _FORTIFY_SOURCE prefix

Get prefix to a -D_FORTIFY_SOURCE string if it is present in
CFLAGS and apply the prefix to flags added to redefine
_FORTIFY_SOURCE in CFLAGS and CPPFLAGS

* fixes 1569
Merge pull request #1654 from gaurdro/rpm-fortify_source

[RFC] Fix issue 1569: Build fails in rpmbuild environment
Merge pull request #1686 from jszakmeister/include-opts-in-fortify-check

build: include the flags for the build type in the _FORTIFY_SOURCE check
Merge pull request #1588 from equalsraf/tb-no-central-deps

Dont force ../.deps in third-party/CMakeLists.txt use the Makefile instead
vim-patch:7.4.423

Problem:    expand("$shell") does not work as documented.
Solution:   Do not escape the $ when expanding environment variables.

https://code.google.com/p/vim/source/detail?r=v7-4-423