libstdc++: Include <sys/cdefs.h> in os_defines.h for FreeBSD [PR117210]

This is needed so that __LONG_LONG_SUPPORTED is defined before we depend
on it.

libstdc++-v3/ChangeLog:

	PR libstdc++/117210
	* config/os/bsd/dragonfly/os_defines.h: Include <sys/cdefs.h>.
	* config/os/bsd/freebsd/os_defines.h: Likewise.

Author: jwakely

libstdc++-v3/config/os/bsd/dragonfly/os_defines.h

@@ -29,6 +29,8 @@
 // System-specific #define, typedefs, corrections, etc, go here.  This
 // file will come before all others.
 
+#include <sys/cdefs.h> // For __LONG_LONG_SUPPORTED
+
 #define _GLIBCXX_USE_C99 1
 #define _GLIBCXX_USE_C99_STDIO 1
 #define _GLIBCXX_USE_C99_STDLIB 1

libstdc++-v3/config/os/bsd/freebsd/os_defines.h

@@ -29,6 +29,8 @@
 // System-specific #define, typedefs, corrections, etc, go here.  This
 // file will come before all others.
 
+#include <sys/cdefs.h> // For __LONG_LONG_SUPPORTED
+
 #define _GLIBCXX_USE_C99_STDIO 1
 #define _GLIBCXX_USE_C99_STDLIB 1
 #define _GLIBCXX_USE_C99_WCHAR 1