make CMPLX macros available in complex.h in non-c11 mode as well
math: turn off the STRICT_ASSIGN workaround by default the volatile hack in STRICT_ASSIGN is only needed if assignment is not respected and excess precision is kept. gcc -fexcess-precision=standard and -ffloat-store both respect assignment and musl use these flags by default. i kept the macro for now so the workaround may be used for bad compilers in the future.
complex: add C11 CMPLX macros and replace cpack with them
add FORCE_EVAL macro to evaluate float expr for their side effect updated nextafter* to use FORCE_EVAL, it can be used in many other places in the math code to improve readability.
add creal/cimag macros in complex.h (and use them in the functions defs)
don't inline __rem_pio2l so the code size is smaller
fix loads of missing const in new libm, and some global vars (?!) in powl
fix namespace issues for lgamma, etc. standard functions cannot depend on nonstandard symbols
first commit of the new libm! thanks to the hard work of Szabolcs Nagy (nsz), identifying the best (from correctness and license standpoint) implementations from freebsd and openbsd and cleaning them up! musl should now fully support c99 float and long double math functions, and has near-complete complex math support. tgmath should also work (fully on gcc-compatible compilers, and mostly on any c99 compiler). based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from nsz's libm git repo, with some additions (dummy versions of a few missing long double complex functions, etc.) by me. various cleanups still need to be made, including re-adding (if they're correct) some asm functions that were dropped.