"GCC requires the freestanding environment provide memcpy, memmove, memset
and memcmp" [1].
Hence in GNUEABI targets LLVM should not convert 'memops' to their equivalent
'__aeabi_memops'. This convertion violates GCC contract.
The -meabi flag controls whether or not LLVM will modify 'memops' in GNUEABI
targets.
Without -meabi: use the triple default EABI. With -meabi=default: use the triple default EABI. With -meabi=gnu: use 'memops'. With -meabi=4 or -meabi=5: use '__aeabi_memops'. With -meabi set to an unknown value: same as -meabi=default.
[1] https://gcc.gnu.org/onlinedocs/gcc-5.2.0/gcc/Standards.html
Might be nice to spell this as meabi to keep it consistent across clang and opt.