Re-enable MINGW32-specific compile options (#5470)

This reverts a mistake of mine: My change to introduce an "else ifeq" in
#5439 chain missed that there
is [an `else`
clause](https://github.com/dscho/git/blob/31963038164d1a2d78dc46225f8441e8c0fb07a8/config.mak.uname#L739-L742)
that should be used for MINGW32 and MSys (to add large-address-awareness
and use 32-bit `time_t`) but not for CLANGARM64 nor for MINGW64.

config.mak.uname

@@ -728,7 +728,8 @@ ifeq ($(uname_S),MINGW)
 		prefix = /mingw32
 		HOST_CPU = i686
 		BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup
-        else ifeq (MINGW64,$(MSYSTEM))
+        endif
+        ifeq (MINGW64,$(MSYSTEM))
 		prefix = /mingw64
 		HOST_CPU = x86_64
 		BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup