configure.ac: respect 'g' variants of libtool/libtoolize

BSD OS'es (OS X for me) provide GNU tools with prefixed 'g'. To find correct
versions of libtool/libtoolize on those systems search also for
glibtool/glibtoolize.

Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
[yann.morin.1998@free.fr: search for the g-variant first]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <2f1530b54afcb6a00e1d.1395158786@andreas-mbp.er.biessmann.org>
Patchwork-Id: 331467

 diff -dur strace-4.5.15.orig/system.c strace-4.5.15/system.c

 --- strace-4.5.15.orig/system.c	2007-01-17 00:22:36.000000000 +0100

 +++ strace-4.5.15/system.c	2007-07-14 19:28:41.000000000 +0200

 @@ -1612,7 +1612,9 @@

  	{ CTL_KERN, "CTL_KERN" },

  	{ CTL_VM, "CTL_VM" },

  	{ CTL_NET, "CTL_NET" },

 +#ifdef CTL_PROC

  	{ CTL_PROC, "CTL_PROC" },

 +#endif

  	{ CTL_FS, "CTL_FS" },

  	{ CTL_DEBUG, "CTL_DEBUG" },

  	{ CTL_DEV, "CTL_DEV" },