silence warnings under macOS for cc, clang and gcc

Used the following script to check for warnings
not silenced via ${CSILENCE}:

```sh
find ???? -mindepth 1 -maxdepth 1 -type d | while read dir; do
(cd "$dir"; echo =-=-= "$dir" =-=-= ; csilence -v 1 clobber all ; echo ; csilence -v 1 clobber alt)
done 2>&1 | less
```

2012/hou/Makefile

@@ -41,7 +41,7 @@ include ../../var.mk
 CSILENCE= -Wno-error -Wno-implicit-function-declaration -Wno-format-extra-args \
 	-Wno-implicit-int -Wno-missing-field-initializers \
 	-Wno-non-literal-null-conversion -Wno-return-type -Wno-shift-op-parentheses \
-	-Wno-unused-parameter
+	-Wno-unused-parameter -Wno-deprecated-non-prototype
 
 # Common C compiler warning flags
 #