Add --enable-werror configure option.

INSTALL

@@ -630,6 +630,9 @@ The following options are also configurable at runtime:
   --enable-warnings
 	Enable compiler warnings when building sudo with gcc.
 
+  --enable-werror
+	Enable the -Werror compiler option when building sudo with gcc.
+
   --enable-admin-flag
 	Enable the creation of an Ubuntu-style admin flag file
 	the first time sudo is run.

configure

@@ -874,6 +874,7 @@ enable_env_debug
 enable_zlib
 enable_env_reset
 enable_warnings
+enable_werror
 enable_admin_flag
 enable_nls
 with_selinux
@@ -1534,6 +1535,7 @@ Optional Features:
   --enable-zlib[=PATH]    Whether to enable or disable zlib
   --enable-env-reset      Whether to enable environment resetting by default.
   --enable-warnings       Whether to enable compiler warnings
+  --enable-werror         Whether to enable the -Werror compiler option
   --enable-admin-flag     Whether to create a Ubuntu-style admin flag file
   --disable-nls           Disable natural language support using gettext
   --enable-gss-krb5-ccache-name
@@ -5505,6 +5507,22 @@ $as_echo "$as_me: WARNING: Ignoring unknown argument to --enable-warnings: $enab
 fi
 
 
+# Check whether --enable-werror was given.
+if test "${enable_werror+set}" = set; then :
+  enableval=$enable_werror;  case "$enableval" in
+    yes)    if test X"$with_devel" != X"yes" -a -n "$GCC"; then
+		CFLAGS="${CFLAGS} -Werror"
+	    fi
+	    ;;
+    no)	    ;;
+    *)	    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Ignoring unknown argument to --enable-werror: $enableval" >&5
+$as_echo "$as_me: WARNING: Ignoring unknown argument to --enable-werror: $enableval" >&2;}
+	    ;;
+  esac
+
+fi
+
+
 # Check whether --enable-admin-flag was given.
 if test "${enable_admin_flag+set}" = set; then :
   enableval=$enable_admin_flag;  case "$enableval" in

configure.in

@@ -1304,6 +1304,19 @@ AC_ARG_ENABLE(warnings,
   esac
 ])
 
+AC_ARG_ENABLE(werror,
+[AS_HELP_STRING([--enable-werror], [Whether to enable the -Werror compiler option])],
+[ case "$enableval" in
+    yes)    if test X"$with_devel" != X"yes" -a -n "$GCC"; then
+		CFLAGS="${CFLAGS} -Werror"
+	    fi
+	    ;;
+    no)	    ;;
+    *)	    AC_MSG_WARN([Ignoring unknown argument to --enable-werror: $enableval])
+	    ;;
+  esac
+])
+
 AC_ARG_ENABLE(admin-flag,
 [AS_HELP_STRING([--enable-admin-flag], [Whether to create a Ubuntu-style admin flag file])],
 [ case "$enableval" in