Bugzilla bug 172651: added a necessary test for MinGW gcc in rules.mk.

Do not install 'nsinstall' to avoid overwriting Mozilla's 'nsinstall'.
r=cls.
Modified Files:
	rules.mk nsinstall/Makefile

security/coreconf/nsinstall/Makefile

@@ -52,6 +52,7 @@ ifeq (,$(filter-out OS2 WIN%,$(OS_TARGET)))
 PROGRAM		=
 else
 TARGETS		= $(PROGRAM) $(PLSRCS:.pl=)
+INSTALL		= true
 endif
 
 ifdef NATIVE_CC

security/coreconf/rules.mk

@@ -301,7 +301,7 @@ get_objs:
 $(LIBRARY): $(OBJS)
 	@$(MAKE_OBJDIR)
 	rm -f $@
-ifeq (,$(filter-out WIN%,$(OS_TARGET)))
+ifeq (,$(filter-out _WIN%,$(NS_USE_GCC)_$(OS_TARGET)))
 	$(AR) $(subst /,\\,$(OBJS))
 else
 	$(AR) $(OBJS)