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`.

1996/huffman/Makefile

@@ -39,7 +39,7 @@ include ../../var.mk
 # Common C compiler warnings to silence
 #
 CSILENCE= -Wno-error -Wno-implicit-function-declaration -Wno-parentheses \
-	-Wno-strict-prototypes
+	-Wno-strict-prototypes -Wno-deprecated-declarations -Wno-implicit-int
 
 # Common C compiler warning flags
 #

1996/jonth/Makefile

@@ -40,7 +40,8 @@ include ../../var.mk
 #
 CSILENCE= -Wno-char-subscripts -Wno-error -Wno-implicit-function-declaration \
 	-Wno-infinite-recursion -Wno-return-type -Wno-string-plus-int \
-	-Wno-unsequenced -Wno-unused-parameter -Wno-deprecated-non-prototype
+	-Wno-unsequenced -Wno-unused-parameter -Wno-deprecated-non-prototype \
+	-Wno-implicit-int
 
 # Common C compiler warning flags
 #

1996/rcm/Makefile

@@ -38,7 +38,8 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-empty-body -Wno-shift-op-parentheses -Wno-strict-prototypes
+CSILENCE= -Wno-empty-body -Wno-shift-op-parentheses -Wno-strict-prototypes \
+	  -Wno-implicit-int
 
 # Common C compiler warning flags
 #

1996/schweikh3/Makefile

@@ -84,7 +84,7 @@ CC= cc
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
 CSILENCE+= -Wno-comma -Wno-date-time -Wno-double-promotion \
-	-Wno-poison-system-directories -Wno-unreachable-code
+	-Wno-poison-system-directories -Wno-unreachable-code -Wno-c99-compat
 #
 CWARN+= -Weverything
 #