Bump glib to a more recent upstream version (2.48.1), which happens to fix
the following build issue:
m4macros/glib-gettext.m4:39: error: m4_copy: won't overwrite defined macro: glib_DEFUN
Also bump to the respective glibmm 2.48.1 version. This, in turn,
requires a newer libsigc++, so bump that to 2.9.2 as well.
VER_ZLIB=1.2.8
VER_PCRE=8.38
VER_LIBFFI=3.2.1
-VER_GLIB=2.45.4
-VER_GLIB_SHORT=2.45
-VER_GLIBMM=2.45.41
-VER_GLIBMM_SHORT=2.45
-VER_LIBSIGCXX=2.6.2
-VER_LIBSIGCXX_SHORT=2.6
+VER_GLIB=2.48.1
+VER_GLIB_SHORT=2.48
+VER_GLIBMM=2.48.1
+VER_GLIBMM_SHORT=2.48
+VER_LIBSIGCXX=2.9.2
+VER_LIBSIGCXX_SHORT=2.9
VER_LIBZIP=1.1
VER_LIBFTDI1=1.2
VER_LIBUSB=1.0.19