package/poppler: bump version to 0.77.0

For the version bump, the makefile had to be rewritten for CMake, as
the project moved from autotools to CMake.

Signed-off-by: Olivier Schonken <olivier.schonken@gmail.com>
[Thomas:
 - update again to the lastest poppler version, 0.77.0
 - drop license related changes, since the licensing terms haven't
   changed, and they are not completely clear
 - keep the openjpeg, jpeg and lcms2 dependencies optionals
 - explicitly enable/disable more dependencies
 - bump gcc version dependency to gcc 5.x, and update the Config.in
   comment accordingly
 - don't introduce many sub-options, simply rely on the availability
   of dependencies, or on BR2_SOFT_FLOAT
 - drop libx11/libxext dependencies, no longer used]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>