autopoint: disable m4_include and m4_esyscmd when tracing

* autopoint.in (func_trace): Disable m4_include and m4_esyscmd.
* gettextize.in (func_trace): Likewise.
Reported by Bernhard Voelker in
<https://lists.gnu.org/archive/html/bug-gettext/2013-11/msg00011.html>
and suggested by Eric Blake at <https://savannah.gnu.org/bugs/?40083>.
xgettext: Add E4X support to JavaScript scanner

Reported by Piotr Drąg at: <https://savannah.gnu.org/bugs/?40125>.
* src/xgettext.h (enum lexical_context_ty): New enumeration items
lc_xml_open_tag, lc_xml_close_tag, lc_xml_content.
* src/x-javascript.c (phase5_scan_xml_markup): New
function.
(phase5_get): Handle '<', '>', '/', '=', '{', and '}' specially
to support E4X.
(enum token_type_ty): New enumeration item token_type_equal.
(xml_element_depth): New variable.
(inside_embedded_in_xml): New variable.
(extract_javascript): Initialize those variables.
* tests/Makefile.am (TESTS): Add xgettext-javascript-6.
* tests/xgettext-javascript-6: New file.
JavaScript E4X: Add more tests
autopoint: Allow user to specify custom autom4te executable

* autopoint.in (func_trace): Allow user to specify autom4te
executable name through $AUTOM4TE envvar.
* gettextize.in (func_trace): Likewise.
Suggested by Eric Blake at
<https://lists.gnu.org/archive/html/bug-gettext/2013-12/msg00006.html>.
libgrep: Fix issues detected by gcc -Wformat-security

* m-fgrep.c (Fcompile): Supply FORMAT argument of error.
* m-regex.c (compile): Likewise.