libsanitizer/mips: always build with largefile support

libsanitizer/mips: always build with largefile support

-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 is always used for mips
when build libsanitizer in LLVM. Thus
   FIRST_32_SECOND_64((_MIPS_SIM == _ABIN32) ? 176 : 160, 216);
instead of
   FIRST_32_SECOND_64((_MIPS_SIM == _ABIN32) ? 160 : 144, 216);
in sanitizer_platform_limits_posix.h.

To keep sync with LLVM and to make the code simple, we use the
largefile options always.

libsanitizer/
	* configure.ac: set -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
	always for mips*.
	* configure: Regenerate.