File mono-510-build-fix.patch of Package mono-tools
diff -uprN mono-tools-4.2.old/gendarme/options.make mono-tools-4.2/gendarme/options.make
--- mono-tools-4.2.old/gendarme/options.make 2014-10-04 13:56:08.000000000 +0400
+++ mono-tools-4.2/gendarme/options.make 2018-03-24 02:02:35.807203718 +0300
@@ -2,5 +2,5 @@
COMMON_OPTIONS := -debug+ -d:TRACE $(if $(DEBUG),-d:DEBUG -checked+,-optimize+)
COMMON_OPTIONS += -nowarn:1591 # Missing XML comment
-GENDARME_OPTIONS := $(COMMON_OPTIONS) -warn:4 -warnaserror+
+GENDARME_OPTIONS := $(COMMON_OPTIONS) -warn:4
TESTS_OPTIONS := $(COMMON_OPTIONS) -warn:0