[ASan] Print exact source location of global variables in error reports.

See https://code.google.com/p/address-sanitizer/issues/detail?id=299 for the
original feature request.

Introduce llvm.asan.globals metadata, which Clang (or any other frontend)
may use to report extra information about global variables to ASan
instrumentation pass in the backend. This metadata replaces
llvm.asan.dynamically_initialized_globals that was used to detect init-order
bugs. llvm.asan.globals contains the following data for each global:
  1) source location (file/line/column info);
  2) whether it is dynamically initialized;
  3) whether it is blacklisted (shouldn't be instrumented).

Source location data is then emitted in the binary and can be picked up
by ASan runtime in case it needs to print error report involving some global.
For example:

  0x... is located 4 bytes to the right of global variable 'C::array' defined in '/path/to/file:17:8' (0x...) of size 40

These source locations are printed even if the binary doesn't have any
debug info.

This is an ABI-breaking change. ASan initialization is renamed to
__asan_init_v4(). Pre-built libraries compiled with older Clang will not work
with the fresh runtime.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212188 91177308-0d34-0410-b5e6-96231b3b80d8
ARCMigrate: simplify diagnostic handling

Recent enhancements in the diagnostics engine mean that
TransformActions::report() no longer needs to duplicate this suppression logic.

That's great because the old code was flawed and would have attached notes to
the wrong primary diagnostic in non-trivial use.

With these changes it becomes safe to use reportNote() freely in the migration
tool.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212191 91177308-0d34-0410-b5e6-96231b3b80d8
Update the MSVC Compatibility document

It hasn't been updated to reflect the progress we've made.  We've fuzz
tested VFTables, VBTables, layout, and RTTI data.  We support lambdas
that are compatible with their scheme.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212193 91177308-0d34-0410-b5e6-96231b3b80d8
CodeGen: make target builtins support languages

This extends the target builtin support to allow language specific annotations
(i.e. LANGBUILTIN).  This is to allow MSVC compatibility whilst retaining the
ability to have EABI targets use a __builtin_ prefix.  This is merely to allow
uniformity in the EABI case where the unprefixed name is provided as an alias in
the header.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212196 91177308-0d34-0410-b5e6-96231b3b80d8