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.

2004/schnitzi/Makefile

@@ -38,8 +38,10 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-deprecated-declarations -Wno-error -Wno-implicit-function-declaration \
-	-Wno-format-extra-args -Wno-strict-prototypes
+CSILENCE= -Wno-deprecated-declarations -Wno-error \
+	  -Wno-implicit-function-declaration -Wno-builtin-declaration-mismatch \
+	  -Wno-stringop-truncation -Wno-unused-value -Wno-format-extra-args \
+	  -Wno-strict-prototypes
 
 # Common C compiler warning flags
 #
@@ -85,7 +87,8 @@ CC= cc
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
 CSILENCE+= -Wno-comma -Wno-conditional-uninitialized -Wno-missing-prototypes \
-	-Wno-poison-system-directories
+	   -Wno-implicit-int-float-conversion -Wno-unknown-warning-option \
+	   -Wno-unsafe-buffer-usage -Wno-poison-system-directories
 #
 CWARN+= -Weverything
 #