silence compiler warnings for macOS

After silencing compiler warnings for RHEL 9 Linux,
we silence the result on macOS for
Apple clang version 15.0.0 (clang-1500.3.9.4).

1988/dale/Makefile

@@ -41,7 +41,8 @@ include ../../var.mk
 CSILENCE= -Wno-implicit-function-declaration -Wno-implicit-int -Wno-keyword-macro \
 	  -Wno-pointer-to-int-cast -Wno-return-type -Wno-unused-value \
 	  -Wno-deprecated-non-prototype -Wno-builtin-declaration-mismatch \
-	  -Wno-implicit-fallthrough -Wno-missing-parameter-type
+	  -Wno-implicit-fallthrough -Wno-missing-parameter-type \
+	  -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #

1988/isaak/Makefile

@@ -43,7 +43,8 @@ CSILENCE= -Wno-comma -Wno-implicit-function-declaration -Wno-format-insufficient
 	  -Wno-missing-variable-declarations -Wno-poison-system-directories -Wno-return-type \
 	  -Wno-shadow -Wno-shift-op-parentheses -Wno-strict-prototypes -Wno-unreachable-code \
 	  -Wno-unused-macros -Wno-int-conversion -Wno-macro-redefined -Wno-parentheses \
-	  -Wno-builtin-declaration-mismatch -Wno-format -Wno-missing-parameter-type
+	  -Wno-builtin-declaration-mismatch -Wno-format -Wno-missing-parameter-type \
+	  -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #

1988/phillipps/Makefile

@@ -42,7 +42,7 @@ CSILENCE= -Wno-pedantic -Wno-logical-not-parentheses -Wno-implicit-function-decl
 	  -Wno-incompatible-pointer-types -Wno-int-conversion -Wno-pointer-to-int-cast \
 	  -Wno-pointer-integer-compare -Wno-compare-distinct-pointer-types \
 	  -Wno-deprecated-non-prototype -Wno-implicit-int -Wno-missing-parameter-type \
-	  -Wno-return-type
+	  -Wno-return-type -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #

1988/reddy/Makefile

@@ -40,7 +40,7 @@ include ../../var.mk
 #
 CSILENCE= -Wno-pedantic -Wno-error -Wno-implicit-function-declaration -Wno-parentheses \
 	  -Wno-return-type -Wno-deprecated-declarations -Wno-deprecated-non-prototype \
-	  -Wno-implicit-int -Wno-missing-parameter-type
+	  -Wno-implicit-int -Wno-missing-parameter-type -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #

1988/robison/Makefile

@@ -40,7 +40,7 @@ include ../../var.mk
 #
 CSILENCE= -Wno-error -Wno-implicit-function-declaration -Wno-deprecated-non-prototype \
 	  -Wno-implicit-int -Wno-misleading-indentation -Wno-missing-parameter-type \
-	  -Wno-return-type
+	  -Wno-return-type -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #