For now, compile all of contrib/gdtoa without requiring strict aliasing,

since it is using type punning of union members, and clang does not yet
support gcc's extensions which allow this (refer to
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#Type%2dpunning
for more information).

This should fix strtod(3) return values for the lang/julia port, so it
does not fail on an assertion during its build.

PR:		216770

lib/libc/gdtoa/Makefile.inc

@@ -17,4 +17,5 @@ MISRCS+=gdtoa_${src}
 CLEANFILES+=gdtoa_${src}
 gdtoa_${src}: ${SRCTOP}/contrib/gdtoa/${src} .NOMETA
 	ln -sf ${.ALLSRC} ${.TARGET}
+CFLAGS.gdtoa_${src}+=-fno-strict-aliasing
 .endfor