warning-free build without -Wno-missing-field-initializers

Also removes a GCC_WARN usage and the need for
#pragma GCC diagnostic ignored "-Wmissing-braces"
for src/decl.c when using gcc.

sys/unix/hints/include/compiler.370

@@ -51,7 +51,7 @@ endif   # clang
 #CXX=clang++ -std=gnu++11
 
 CFLAGS=$(CCFLAGS) -I../include -DNOTPARMDECL
-CFLAGS+=-Wall -Wextra -Wno-missing-field-initializers \
+CFLAGS+=-Wall -Wextra \
 	-Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wwrite-strings
 CFLAGS+=-pedantic
 CFLAGS+=-Wmissing-declarations
@@ -67,7 +67,7 @@ CFLAGS+=-Wold-style-definition
 CFLAGS+=-Wstrict-prototypes
 
 CCXXFLAGS = -g -I../include -DNOTPARMDECL
-CCXXFLAGS+=-Wall -Wextra -Wno-missing-field-initializers \
+CCXXFLAGS+=-Wall -Wextra \
         -Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wwrite-strings
 CCXXFLAGS+=-pedantic
 CCXXFLAGS+=-Wmissing-declarations