[PowerPC] Add support for -mlongcall
The "long call" option forces the use of the indirect calling
sequence for all calls (even those that don't really need it). GCC
provides this option; This is helpful, under certain circumstances,
for building very-large binaries, and some other specialized use
cases.
Fixes PR19098.
Pull in r280041 from upstream clang trunk (by Hal Finkel):
[PowerPC] Add support for -mlongcall
Add support for GCC's PowerPC -mlongcall option; the backend supports
the corresponding target feature as of r280040.
Fixes PR19098.
b6054a7b70