Check --enable-xxx and --with-xxx options in configure by default

Give an error if an unknown option is specified because this is very helpful
for catching typos which happen quite frequently in practice, considering the
number of options that we have.

To explicitly allow unknown options, i.e. restore the old behaviour,
--disable-option-checking can be used.

configure

@@ -623,6 +623,7 @@ ac_includes_default="\
 #endif"
 
 enable_option_checking=no
+enable_option_checking=fatal
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
 CPPUNIT_CONFIG
@@ -40281,6 +40282,8 @@ $as_echo "$as_me: WARNING: unrecognized options: $ac_unrecognized_opts" >&2;}
 fi
 
 
+
+
 echo
 echo "Configured wxWidgets ${WX_VERSION} for \`${host}'"
 echo ""

configure.in

@@ -8300,6 +8300,19 @@ fi dnl wxWITH_SUBDIRS
 
 AC_OUTPUT
 
+dnl Enable strict option checking by default because typos in --enable-xxx is
+dnl a much more common case than wanting to explicitly pass an option unknown
+dnl to the main configure script (this one) to a configure scripts in a
+dnl subdirectory (e.g. src/tiff or src/expat). If someone really needs to do
+dnl the latter, --disable-option-checking would need to be explicitly used.
+dnl
+dnl Notice that we need to do this at the very end of configure script as
+dnl otherwise this would be overridden by AC_CONFIG_SUBDIRS() which disables
+dnl option checking. And we need to use m4_divert_text() because we want this
+dnl to appear in the beginning of the generated file, before the code parsing
+dnl the options.
+m4_divert_text([DEFAULTS],[enable_option_checking=fatal])
+
 dnl report how we have been configured
 echo
 echo "Configured wxWidgets ${WX_VERSION} for \`${host}'"