Openlibm

A list of issues that are related to the differences in math libraries among different systems:

bug #57071	Fix math.h and function names that block 64-bit double
bug #55538	logspace BIST tests fail when Octave built with LLVM libc++
bug #62212	Wrong unsigned integer overflow with clang
bug #49984	fabs missing from libm implementation.
bug #61812	Math constants (e.g. M_PI) are not part of C/C++ standard
bug #49091	MinGW std::acosh less accurate than Linux versions
bug #60784	Inconsistent behavior for boolean matrix types with matrix functions
bug #45481	rem and fmod may give very wrong results for large arguments
bug #61715	Inconsistent NaN results for exponential function (0+0i)^0 with libc++ and libstdc++
bug #45746	Incorrect results of trigonometric functions gsl_sf_sin and gsl_sf_cos