compat/nedmalloc: don't force NDEBUG on the rest of git

Define the nedmalloc feature configuration macros for nedmalloc.o, only.
This keeps assert(3) working for the rest of the git source; it was
turned off for nedmalloc users before by defining NDEBUG globally.

Also remove -DUSE_NED_ALLOCATOR as this macro isn't used anywhere.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -1448,7 +1448,7 @@ ifdef NO_REGEX
 endif
 
 ifdef USE_NED_ALLOCATOR
-       COMPAT_CFLAGS += -DUSE_NED_ALLOCATOR -DOVERRIDE_STRDUP -DNDEBUG -DREPLACE_SYSTEM_ALLOCATOR -Icompat/nedmalloc
+       COMPAT_CFLAGS += -Icompat/nedmalloc
        COMPAT_OBJS += compat/nedmalloc/nedmalloc.o
 endif
 
@@ -1879,6 +1879,11 @@ ifdef NO_EXPAT
 http-walker.s http-walker.o: EXTRA_CPPFLAGS = -DNO_EXPAT
 endif
 
+ifdef USE_NED_ALLOCATOR
+compat/nedmalloc/nedmalloc.o: EXTRA_CPPFLAGS = \
+	-DNDEBUG -DOVERRIDE_STRDUP -DREPLACE_SYSTEM_ALLOCATOR
+endif
+
 git-%$X: %.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)