Configure: Rewrite the macro for checking Xft2 version
The original macro used over-complicated things, like:
- useless uses of 'eval',
- split AC_CACHE_CHECK construct (AC_MSG_CHECKING + AC_CACHE_VAL +
AC_MSG_RESULT)
- dubious variable name (CPPFLAGS_old, which is not the "old" value but
the "saved" value for a temporary change)
- variable CPPFLAGS was changed at wrong hierarchy level
- calculate the integer value for XFT_VERSION in m4 instead generating
shell commands that had to do it on user side
- indentation was missing
Signed-off-by: Christophe CURIS <christophe.curis@free.fr>