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.

1990/dds/Makefile

@@ -38,10 +38,12 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-builtin-requires-header -Wno-char-subscripts -Wno-conditional-type-mismatch \
-	-Wno-empty-body -Wno-error -Wno-implicit-function-declaration \
-	-Wno-incompatible-library-redeclaration -Wno-parentheses -Wno-implicit-int \
-	-Wno-deprecated-non-prototype -Wno-return-type -Wno-strict-prototypes
+CSILENCE= -Wno-builtin-requires-header -Wno-char-subscripts \
+	  -Wno-conditional-type-mismatch -Wno-empty-body -Wno-error \
+	  -Wno-implicit-function-declaration -Wno-incompatible-library-redeclaration \
+	  -Wno-parentheses -Wno-implicit-int -Wno-deprecated-non-prototype \
+	  -Wno-return-type -Wno-strict-prototypes -Wno-builtin-declaration-mismatch \
+	  -Wno-misleading-indentation -Wno-unused-value
 
 # Common C compiler warning flags
 #
@@ -87,8 +89,8 @@ CC= cc
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
 CSILENCE+= -Wno-comma -Wno-missing-prototypes -Wno-missing-variable-declarations \
-	-Wno-poison-system-directories -Wno-shadow -Wno-shorten-64-to-32 \
-	-Wno-unreachable-code-return
+	   -Wno-poison-system-directories -Wno-shadow -Wno-shorten-64-to-32 \
+	   -Wno-unreachable-code-return -Wno-unknown-warning-option -Wno-unsafe-buffer-usage
 #
 CWARN+= -Weverything
 #