add attributes for clang compiler
cmake: runtime: On Darwin, malloc is always aligned to a 16 byte boundary, to work with Altivec and SSE (etc) SIMD; so, set ALIGNED_MALLOC to 16 for those Darwin systems that do not have posix_memalign.
runtime: fix comment in posix_memalign.
tag_checker.h: fix unitialized d_has_next_tag; coverity 1128348

keeping style-compatible with the original file, just to keep the commit small
check_lfsr_32k: fix < instead of <<; coverity 1046413
call do_update after calling open in the file source constructor,
otherwise if seek is called before work, a segmentation fault will occur
as d_fp is null
runtime: fixed order of initializing warning in tag_checker constructor.