make: Clean up WERROR handling

Makefile.include

@@ -129,13 +129,13 @@ endif
 WERROR ?= 1
 export WERROR
 ifeq ($(WERROR),1)
-  CFLAGS += -Wall -Werror -Wextra
+  CFLAGS += -Werror
 endif
 
 WPEDANTIC ?= 0
 export WPEDANTIC
 ifeq ($(WPEDANTIC),1)
-    CFLAGS += -Wpedantic -pedantic-errors
+  CFLAGS += -Wpedantic
 endif
 
 # remove this once codebase is adapted

makefiles/cflags.inc.mk

@@ -57,8 +57,8 @@ endif
 # Forbid common symbols to prevent accidental aliasing.
 CFLAGS += -fno-common
 
-# Enable all default warnings
-CFLAGS += -Wall
+# Enable all default warnings and all extra warnings
+CFLAGS += -Wall -Wextra
 
 # Warn if a user-supplied include directory does not exist.
 CFLAGS += -Wmissing-include-dirs