add AC_CHECK_CC_OPT from ac-archive. check for cfmakeraw, sys/select.h,

add AC_CHECK_CC_OPT from ac-archive. check for cfmakeraw, sys/select.h,

* acinclude.m4: add AC_CHECK_CC_OPT from ac-archive.
* configure.in: check for cfmakeraw, sys/select.h, compiler support for -std=
	(#99698)
* doc/boxes.txt: change reference to online Docbook reference to the charts at
	the Unicode web site.
* src/dumpkeys.c: make a best-effort at making a terminal raw on systems where
	cfmakeraw() isn't available, from patch by Brian Cameron.  Wait for up
	to 1/50 of a second for more bytes we'll consider to be part of a
	sequence.
* src/pty.c(getpt): ensure that the new terminal is opened in non-blocking mode.
* src/trie.c: use g_unichar_digit_value() instead of subtracting '0'.
* src/vte.c: don't declare the xft_textitem member on non-Xft2 systems, because
	it uses an Xft2-specific type (#99685).
* src/vteapp.c: add $pkgdatadir/fonts to the font path for use when testing.