Initial collection of some C99 math functions.
Added a gamma function implementation based directly on specfun Fortran code.
Additional math functions implemented.  Some may be deficient due to a lack of exception handling.
Fixed some copypasta errors
Updates to math library headers.
Fixes to allow building and minor typos.
Switched to a specfun implementation of lgamma to allow 16-bit builds.
New implementations of erf and lgamma based on SPECFUN package so that 16-bit builds are now possible.
Updated generic log1p implemented based on SLATEC code.
Rewrite of most FDLIBM ports to more direct calculations to avoid issues with 16-bit targets.
Fixed minor warning in expm1.c
Fixes to logb/ilogb/scalbn to allow 16-bit compilation.
Fixes to mathlib's builder.ctl to support tests.  Fixes to the qa makefile in mathlib to make it actually work.
Added cbrt, scalbn, and nxtafter to 16-bit builds.  Fixes to associated files.
Fixed mis-definition in nextafter
Fix to nextafter to include signs
Added library paths for release to the QA makefile for mathlib
Fixes to various c99 math functions based on test results.  Fixes to some mathlib QA tests.  Added defined ilogb() results to math header.
Fixed logb() to return positive infinity for zero on all platforms.
Expanded test platforms again.