Pass ENABLE_DEBUG into external/zlib

Change-Id: I3aea7c64acfc933e4df901d4de349708a3331bcd
Reviewed-on: https://gerrit.libreoffice.org/68811
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/zlib/StaticLibrary_zlib.mk

@@ -29,4 +29,8 @@ $(eval $(call gb_StaticLibrary_add_generated_cobjects,zlib,\
 	UnpackedTarball/zlib/zutil \
 ))
 
+ifeq ($(ENABLE_DEBUG),TRUE)
+$(eval $(call gb_StaticLibrary_add_cflags,zlib,-DZLIB_DEBUG))
+endif
+
 # vim: set noet sw=4 ts=4:

external/zlib/StaticLibrary_zlib_x64.mk

@@ -32,4 +32,8 @@ $(eval $(call gb_StaticLibrary_add_x64_generated_cobjects,zlib_x64,\
 	UnpackedTarball/zlib/x64/zutil \
 ))
 
+ifeq ($(ENABLE_DEBUG),TRUE)
+$(eval $(call gb_StaticLibrary_add_cflags,zlib_x64,-DZLIB_DEBUG))
+endif
+
 # vim: set noet sw=4 ts=4: