…s and exit/abort

basop32_threadsafe.c, enh40_threadsafe.c, basop32_threadsafe.h, and enh40_threadsafe.h are modified basop and enh40 files for use with ITU and ETSI codecs. The modifications make some functions static inline, allow disable terminations not suitable for Linux libs such as exit() and replace with alternate error handling and message logging, and allow removal or alternative usage of global variables Overflow and Carry. For example, sub_ovf() is identical to sub() but includes a stack based Overflow param. Definitions such as USE_BASOPS_INLINE, EXCLUDE_BASOPS_NOT_USED, USE_BASOPS_OVERFLOW_GLOBAL_VAR, USE_BASOPS_CARRY_GLOBAL_VAR, and USE_BASOPS_EXIT allow fine-grain control of modification behavior. Also:

-2017 STL format & indentation is maintained
-modifications include detailed comments
-for testing with standard codec builds, modify your Makefile to temporarily rename basop32_threadsafe.h to basop32.h and enh40_threadsafe.h to enh40.h
-so far bit-exact tested with some codecs, but no separate functional test is provided for basop