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.

2018/endoh2/Makefile

@@ -83,7 +83,8 @@ CC= cc
 #
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
-CSILENCE+= -Wno-missing-variable-declarations -Wno-poison-system-directories
+CSILENCE+= -Wno-missing-variable-declarations -Wno-poison-system-directories \
+	   -Wno-unsafe-buffer-usage
 #
 CWARN+= -Weverything
 #