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/endoh3/Makefile

@@ -39,7 +39,8 @@ include ../../var.mk
 # Common C compiler warnings to silence
 #
 CSILENCE= -Wno-error -Wno-implicit-function-declaration -Wno-implicit-int \
-	-Wno-main -Wno-deprecated-non-prototype -Wno-unused-parameter
+	  -Wno-main -Wno-deprecated-non-prototype -Wno-unused-parameter \
+	  -Wno-builtin-declaration-mismatch
 
 # Common C compiler warning flags
 #
@@ -85,8 +86,9 @@ CC= cc
 ifeq "$(findstring $(CLANG),${CC})" "$(CLANG)"
 #
 CSILENCE+= -Wno-comma -Wno-double-promotion -Wno-float-conversion \
-	-Wno-implicit-float-conversion -Wno-missing-variable-declarations \
-	-Wno-newline-eof -Wno-pedantic -Wno-poison-system-directories
+	   -Wno-implicit-float-conversion -Wno-missing-variable-declarations \
+	   -Wno-newline-eof -Wno-pedantic -Wno-poison-system-directories \
+	   -Wno-unknown-warning-option
 #
 CWARN+= -Weverything
 #