[libc] Add math functions to AMD/NVPTX libm

Related to D152486.  The following functions are included in this revision: `acosf`, `acoshf`, `asinf`, `asinhf`, `atanf`, `atanhf`, `ceil`, `ceilf`, `copysign`, `copysignf`, `cos`, `cosf`, `cosh`, `coshf`, `exp10f`, `exp2f`, `expf`, `expm1f`, `fabs`, `fabsf`, `fdim`, `fdimf`, `floor`, `floorf`, `fma`, `fmaf`, `fmax`, `fmaxf`, `fmin`, `fminf`, `fmod`, `fmodf`, `frexp`, `frexpf`, `hypot`, `hypotf`, `ilogb`, `ilogbf`, `ldexp`, `ldexpf`, `llrint`, `llrintf`, `llround`, `llroundf`, `pow`, and `powf`.

Reviewed By: jhuber6

Differential Revision: https://reviews.llvm.org/D152603