silence most warnings under macOS

For macOS Apple clang version 15.0.0 (clang-1500.3.9.4)
compiler, we have silenced the warnings that can be silenced.

We also updated `.gitignore` for `2014/maffiodo2` and `1995/vanschnitz`.

1992/imc/Makefile

@@ -39,7 +39,7 @@ include ../../var.mk
 # Common C compiler warnings to silence
 #
 CSILENCE= -Wno-error -Wno-implicit-function-declaration -Wno-format \
-	-Wno-deprecated-non-prototype
+	-Wno-deprecated-non-prototype -Wno-implicit-int
 
 # Common C compiler warning flags
 #
@@ -87,7 +87,8 @@ ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 CSILENCE+= -Wno-error -Wno-implicit-function-declaration -Wno-format \
 	-Wno-missing-variable-declarations -Wno-poison-system-directorie \
 	-Wno-poison-system-directories -Wno-unknown-warning-option \
-	-Wno-float-conversion -Wno-shorten-64-to-32 -Wno-sign-conversion
+	-Wno-float-conversion -Wno-shorten-64-to-32 -Wno-sign-conversion \
+	-Wno-disabled-macro-expansion
 #
 CWARN+= -Weverything
 #