Breakpad: Fix build with new clang versions.
gcc has a single exception setting for all languages. Saying -fno-exceptions
in gcc disables exceptions and cleanups for cc files, but has no effect for mm
files.
In clang, -fno-exceptions only disables c++ exceptions, but keeps objective-c
exceptions and cleanups enabled.
http://llvm.org/viewvc/llvm-project?view=revision&revision=220714 changed
__EXCEPTIONS to be defined for clang when cleanups are enabled, independent of
if c++ exceptions are enabled. (This was necessary to have clang work with
glibc which looks at __EXCEPTIONS to decide if cleanups are enabled.)
Breakpad tried to use __EXCEPTIONS to figure out if c++ exceptions are enabled.
In cc files, this works: -fno-exceptions will disable c++ exceptions and
cleanups. But in mm files, -fno-exceptions will disable c++ exceptions and
objective-c exceptions will still be enabled, and so cleanups must run and hence
__EXCEPTIONS is defined.
To make things work with both old and new compilers, do the try/catch hack in
mm files either if __EXCEPTIONS is not defined (for old compilers) or if the
compiler is clang and __has_feature(cxx_exceptions) isn't set (which will work
for new clangs too, and which cleanly maps to if c++ exceptions are enabled).
