silence compiler warnings for RHEL 9 Linux

We updated ${CSILENCE} Makefile variables for entries in an attempt to
minimize compiler warnings.  This was tested using
gcc version 11.4.1 20230605 (Red Hat 11.4.1-2) (GCC).

TODO: Recheck macOS clang to see if any new warnings have occur
      under macOS clang.

2013/cable1/Makefile

@@ -39,7 +39,7 @@ include ../../var.mk
 # Common C compiler warnings to silence
 #
 CSILENCE= -Wno-bool-operation -Wno-error -Wno-implicit-function-declaration \
-	-Wno-implicit-int
+	  -Wno-implicit-int
 
 # Common C compiler warning flags
 #
@@ -84,7 +84,7 @@ CC= cc
 #
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
-CSILENCE+= -Wno-cast-align -Wno-poison-system-directories
+CSILENCE+= -Wno-cast-align -Wno-poison-system-directories -Wno-unsafe-buffer-usage
 #
 CWARN+= -Weverything
 #