gdb: fix mips/musl builds.

srcpkgs/gdb/template

@@ -31,6 +31,9 @@ build_options_default="gdbserver python"
 # Both options cannot be enabled at the same time
 vopt_conflict gdbserver static
 
+post_extract() {
+	sed -i 's,sgidefs.h,asm/sgidefs.h,' gdb/mips-linux-nat.c
+}
 post_install() {
 	# resolve conflicts with binutils
 	rm -rf ${DESTDIR}/usr/include ${DESTDIR}/usr/lib