Reland of #84991
A downstream overlay mode user ran into issues with the isnan macro not
working in our sources with a specific libc configuration. This patch
replaces the last direct includes of math.h with our internal
math_macros.h, along with the necessary build system changes.
Some ctype functions are called from other libc functions (e.g. isspace
is used in atoi). By moving ctype_utils.h to __support it becomes easier
to include just the implementations of these functions. For these
reasons the implementation for isspace was moved into
ctype_utils as well.
FPUtils was moved to simplify the build order, and to clarify which
files are a part of the actual libc.
Many files were modified to accomodate these changes, mostly changing
the #include paths.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D107600
Also added diffing of a few more math functions. Combining the diff check
for all of these functions helps us meet the OSS fuzz bar of a minimum of
100 program edges.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D91817
