CI: enable compiler warnings

[Akim Demaille]

commit 41c43ef3d7e1b87ce478d85a1f06255f1dee72dd
Author: Akim Demaille <address@hidden>
Date:   Thu Sep 6 14:07:12 2018 +0200

    CI: enable compiler warnings
    
    * .travis.yml: here.
    * README-hacking: We no longer aim at K&R C.

diff --git a/.travis.yml b/.travis.yml
index b21839ea..040f68e9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -122,7 +122,7 @@ before_install:
 
 script:
   - ./bootstrap
-  - ./configure CC="$CC" CXX="$CXX"
+  - ./configure --enable-gcc-warnings CC="$CC" CXX="$CXX"
   - make -j2
   - make check VERBOSE=1 TESTSUITEFLAGS=-j2
 
diff --git a/README-hacking b/README-hacking
index 56761c1c..01d44429 100644
--- a/README-hacking
+++ b/README-hacking
@@ -273,10 +273,7 @@ release:
 - running "make maintainer-check-release" takes care of running
   maintainer-check, maintainer-check-push and maintainer-check-xml.
 
-- Change tests/atlocal/CFLAGS to add your preferred options.  For instance,
-  "-traditional" to check that the parsers are K&R.  Note that it does not
-  make sense for glr.c, which should be ANSI, but currently is actually GNU
-  C, nor for lalr1.cc.
+- Change tests/atlocal/CFLAGS to add your preferred options.
 
 - Test with a very recent version of GCC for both C and C++.  Testing with
   older versions that are still in use is nice too.
@@ -294,7 +291,7 @@ In particular, be sure to read README-release.
 week before a stable release, to give them time to translate them.  Before
 generating the *.pot files, make sure that po/POTFILES.in and
 runtime-po/POTFILES.in list all files with translatable strings.  This
-helps: grep -l '\<_(' *
+helps: grep -l '\<_(' *.
 
 ** Tests
 See above.