libsupport: fix sort_r.h to work on FreeBSD 14 #73

Job	Run time
Build and test with ASAN enabled	1m 42s
Build and test with gcc	1m 3s
Build and test with clang	1m 11s
Cross-compile for Android (aarch64)	36s
Build and test with gcc -m32	1m 34s
Cross-compile for Android (armv7a)	39s
Build and test on macOS	2m 23s
Cross-compile for Android (i686)	40s
Build and test with UBSAN enabled	1m 21s
Build mke2fs on Windows with mingw32	3m 7s
Cross-compile for Android (x86_64)	41s
Build mke2fs on Windows with mingw64	2m 35s
	17m 32s

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