developer: enable pedantic by default

With the codebase firmly C99 compatible and most compilers supporting
newer versions by default, it could help bring visibility to problems.

Reverse the DEVOPTS=pedantic flag to provide a fallback for people stuck
with gcc < 5 or some other compiler that either doesn't support this flag
or has issues with it, and while at it also enable -Wpedantic which used
to be controversial[1] when Apple compilers and clang had widely divergent
version numbers.

Ideally any compiler found to have issues with these flags will be added
to an exception, and indeed, one was added to safely process windows
headers that would use non standard print identifiers, but it is expected
that more will be needed, so it could be considered a weather balloon.

[1] https://lore.kernel.org/git/20181127100557.53891-1-carenas@gmail.com/

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -486,9 +486,9 @@ all::
 #        setting this flag the exceptions are removed, and all of
 #        -Wextra is used.
 #
-#    pedantic:
+#    no-pedantic:
 #
-#        Enable -pedantic compilation.
+#        Disable -pedantic compilation.
 
 GIT-VERSION-FILE: FORCE
 	@$(SHELL_PATH) ./GIT-VERSION-GEN

config.mak.dev

@@ -7,9 +7,11 @@ DEVELOPER_CFLAGS += -Werror
 SPARSE_FLAGS += -Wsparse-error
 endif
 DEVELOPER_CFLAGS += -Wall
-ifneq ($(filter pedantic,$(DEVOPTS)),)
+ifeq ($(filter no-pedantic,$(DEVOPTS)),)
 DEVELOPER_CFLAGS += -pedantic
+DEVELOPER_CFLAGS += -Wpedantic
 ifneq ($(filter gcc5,$(COMPILER_FEATURES)),)
+DEVELOPER_CFLAGS += -Wno-pedantic-ms-format
 DEVELOPER_CFLAGS += -Wno-incompatible-pointer-types
 endif
 endif