[csplit] Removed compiler/mlib; moved all code to stdc.library

[csplit] Removed compiler/mlib; moved all code to stdc.library

 * signgam is now field in struct StdCBase and code has to be adapted.
 * Added some math functions to arosc.static that are used in __vcscan
 * STDC_NOLIBINLINE and STDC_NOLIBDEFINES is now #defined in proto/stdc.h.
   This avoids warning of redefinition of isinf()/isnan() that are now aliased functions but also a macro.
 * Provide dummy libm.a for code that uses -lm switch.
 * Removed usage of arosm lib in mmakefile.src files (not all tested)
   link with stdc where needed.
 * arch specific infinity.c has been replaced with common one
 * From Jason S. McMullan:
   * fenv.c fix for m68k
   * Ignore warnings we've chosen not to fix.

git-svn-id: https://svn.aros.org/svn/aros/trunk@48035 fb15a70f-31f2-0310-bbcc-cdcc74a49acc