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).

1992/adrian/Makefile

@@ -44,7 +44,8 @@ CSILENCE= -Wno-bitwise-op-parentheses -Wno-comment -Wno-deprecated-declarations
 	  -Wno-return-type -Wno-uninitialized -Wno-unused-value -Wno-unused-variable \
 	  -Wno-unused-but-set-variable -Wno-unsequenced -Wno-unused-parameter \
 	  -Wno-empty-translation-unit -Wno-implicit-int \
-	  -Wno-builtin-declaration-mismatch -Wno-sequence-point
+	  -Wno-builtin-declaration-mismatch -Wno-sequence-point \
+	  -Wno-unknown-warning-option
 
 # Common C compiler warning flags
 #