Update patch-r274286-llvm-r201784-asm-dollar.diff, so
test/MC/AsmParser/macros.s is properly deleted when patching.
Pull in r221170 from upstream clang trunk (by Roman Divacky):

  Implement vaarg lowering for ppc32. Lowering of scalars and
  aggregates is supported. Complex numbers are not.

This adds va_args support for PowerPC (32 bit) to clang.

Reviewed by:	jhibbits
MFC after:	3 days
Differential Revision: https://reviews.freebsd.org/D1308
Add clang patch corresponding to r275759.