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
```

2019/dogon/Makefile

@@ -41,7 +41,8 @@ include ../../var.mk
 CSILENCE= -Wno-bitwise-conditional-parentheses -Wno-bitwise-op-parentheses \
 	-Wno-deprecated-declarations -Wno-format -Wno-parentheses \
 	-Wno-shift-op-parentheses -Wno-sign-compare -Wno-unused-variable \
-	-Wno-main-return-type -Wno-return-type -Wno-unused-parameter
+	-Wno-main-return-type -Wno-return-type -Wno-unused-parameter \
+	-Wno-strict-prototypes
 
 # Common C compiler warning flags
 #
@@ -89,7 +90,7 @@ ifeq ($(CC),clang)
 CSILENCE+= -Wno-cast-align -Wno-comma -Wno-conditional-uninitialized \
 	-Wno-missing-prototypes -Wno-missing-variable-declarations \
 	-Wno-poison-system-directories -Wno-shadow -Wno-shorten-64-to-32 \
-	-Wno-sign-conversion -Wno-missing-noreturn
+	-Wno-sign-conversion -Wno-missing-noreturn -Wno-declaration-after-statement
 #
 CWARN+= -Weverything
 #