64-bit integer; use "g_ascii_strtoull()", and, in the configure script,
check whether it's available in GLib (it's not in GLib 1.2[.x]) and, if
not, supply the GLib 2.4.5 version of the routine.
For G_MAXUINT32 and G_MAXUINT64, put a "U" at the end of the constant to
explicitly flag it as unsigned.
svn path=/trunk/; revision=11889
Guy Harris