Throughout, simplify the C99/C11 conditionals, and replace
__STRICT_ANSI__ with the proper internal POSIX macros. The _*_r
reentrant functions need not be guarded (and most haven't been) because
such names in the global scope are reserved to the implementation.
atoff is unique to newlib.
dtoa is not actually exported (_dtoa_r is used internally), is
nonstandard, and the declaration conflicts with the code included in
MySQL, NSPR, and SpiderMonkey.
mktemp was removed in POSIX.1-2001.
The qsort_r declarations are reordered so that the GNU version retains
precedence.
Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>