Fix linux/sparc test to work for sparc64 arch.

Thanks to Myth <frb@wiw.org> for the patch.
Bug #57501 r=cls@seawood.org

xpcom/reflect/xptcall/src/md/unix/Makefile.in

@@ -192,10 +192,12 @@ endif
 #
 # Linux/SPARC
 #
-ifeq ($(OS_ARCH)$(OS_TEST),Linuxsparc)
+ifeq ($(OS_ARCH),Linux)
+ifneq (,$(findstring sparc,$(OS_TEST)))
 CPPSRCS		:= xptcinvoke_sparc_solaris.cpp xptcstubs_sparc_solaris.cpp
 ASFILES		:= xptcinvoke_asm_sparc_linux.s xptcstubs_asm_sparc_solaris.s
 endif
+endif
 #
 # Solaris/SPARC
 #