Update git to v1.8.2.1

This requires a small change to how we handle notes, but otherwise just
works.

Note that we can't use anything from v1.8.0 until v1.8.2.1 because some
of the symbols that we need for graph drawing were made private in
v1.8.0 and this was not reverted until v1.8.2.1.

Signed-off-by: John Keeping <john@keeping.me.uk>
Return const char * in cgit_{httpscheme, hosturl, rooturl}()

The return values of these functions are essentially constant and should
never be modified.

Note that this will introduce a compiler warning when we try to free the
return value of any of these functions. However, given that all of these
currently return statically allocated strings in some cases, they need
to be refactored before this can be done anyway.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Maŕk cgit_environment members const

These reflect the values of environment variables and should never be
changed. Add another xstrdup() when we assign environment variables to
strings that are potentially non-constant.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Do not unnecessarily strdup() environment variables

This reverts the memory duplication introduced in commit 60a2627, while
keeping everything else that has been cleaned up. The environment
variables are never modified, so we do not need to call xstrdupn() here.

Also, remove xstrdupn() which is no longer needed.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Makefile: re-include cgit.conf in cgit.mk

This avoids needed to export every variable that might be used in
cgit.mk from the top-level Makefile.

Signed-off-by: John Keeping <john@keeping.me.uk>
cgit.mk: fix dependency handling

Git calculates the dependency files to be included using a simply
expanded Makefile variable, so it does not include the CGit objects that
are added after that Makefile has been processed.

We therefore need to include the dependency files ourselves in order to
get the dependency calculations right.  Do this.

Signed-off-by: John Keeping <john@keeping.me.uk>
Always #include corresponding .h in .c files

While doing this, remove declarations from header files where the
corresponding definition is declared "static" in order to avoid build
errors.

Also re-order existing headers in ui-*.c so that the file-specific
header always comes immediately after "cgit.h", helping with future
consistency.

Signed-off-by: John Keeping <john@keeping.me.uk>
html.c: Replace strdup() with xstrdup()

Use the xstrdup() wrapper which already bails out if strdup() returns a
NULL pointer.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
ui-refs.c: Remove global header variable

print_tag_header() is only called from cgit_print_tags() -- the
conditional invocation in print_tag() is never executed since
print_tag() is only called by cgit_print_tags() which already executes
print_tag_header() before (resulting in the global variable being always
set in when the condition is evaluated).

Remove the global variable and the conditional invocation.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
ui-refs.c: Refactor print_tag()

The code snippets for OBJ_TAG and other object types are almost
equivalent. Merge them and use a couple of inline if conditions to
select proper fields.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>