Add --enable-developer and make it cause -Werror to be included.

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@21183 ec53bebd-3082-4978-b11e-865c3cabbd6b

cf/wflags.m4

@@ -3,6 +3,13 @@ dnl
 dnl set WFLAGS
 
 AC_DEFUN([rk_WFLAGS],[
+
+AC_ARG_ENABLE(developer, 
+	AS_HELP_STRING([--enable-developer], [enable developer warnings]))
+if test "X$enable_developer" = Xyes; then
+    dwflags="-Werror"
+fi
+
 WFLAGS_NOUNUSED=""
 WFLAGS_NOIMPLICITINT=""
 if test -z "$WFLAGS" -a "$GCC" = "yes"; then
@@ -11,7 +18,7 @@ if test -z "$WFLAGS" -a "$GCC" = "yes"; then
   #   -Wcast-align doesn't work well on alpha osf/1
   #   -Wmissing-prototypes -Wpointer-arith -Wbad-function-cast
   #   -Wmissing-declarations -Wnested-externs
-  WFLAGS="ifelse($#, 0,-Wall, $1)"
+  WFLAGS="ifelse($#, 0,-Wall, $1) $dwflags"
   WFLAGS_NOUNUSED="-Wno-unused"
   WFLAGS_NOIMPLICITINT="-Wno-implicit-int"
 fi