[flang][runtime] Added F128 wrappers for LDBL_MANT_DIG == 113 targets. (#83102)
We can use 'long double' variants of the math functions in this case.
I used the callees from STD namespace, except for the Bessel's
functions.
The new code can be enabled with -DFLANG_RUNTIME_F128_MATH_LIB=libm.
Support for complex data types is pending.