allow for explicit control over -Werror flag similar to how most GNU toolchain packages work

git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1609 b68d4a1b-bc3d-0410-92ed-d4ac073336b7

urjtag/ChangeLog

@@ -3,6 +3,9 @@
   * data/xilinx/PARTS: added xc3s1200e_fg320 and xc2vp30-ffg896 (Florian
     Fainelli)
 
+  * configure.ac: enable -Werror by default only when building out of an scm,
+    and add an explicit --enable-werror option to control it
+
 2009-05-19  Arnim Laeuger  <arniml>
 
   * data/Makefile.am, data/broadcom/bcm6348/bcm6348,

urjtag/configure.ac

@@ -280,8 +280,18 @@ AS_IF([test "x$with_inpout32" = xyes], [
 ])
 
 
-WARNINGCFLAGS="-Werror -Wall -Wmissing-prototypes -Wstrict-prototypes -Wpointer-arith"
+WARNINGCFLAGS="-Wall -Wmissing-prototypes -Wstrict-prototypes -Wpointer-arith"
+AC_ARG_ENABLE([werror],
+  [AS_HELP_STRING([--enable-werror], [build with -Werror])],
+  [], [enable_werror=maybe])
+AS_IF([test "x$enable_werror" = xmaybe -a -d .svn], [
+  enable_werror=yes
+])
+AS_IF([test "x$enable_werror" = xyes], [
+  WARNINGCFLAGS="$WARNINGCFLAGS -Werror"
+])
 AC_SUBST(WARNINGCFLAGS)
+
 CPPFLAGS="-I\$(top_srcdir) -I\$(top_srcdir)/include $CPPFLAGS"