package/glog: switch to cmake

package/glog: switch to cmake

Switch to cmake to fix a build failure on m68k with uclibc because
glog's configure tests wrongly thinks that -fPIE works

By switching to cmake, we can remove the patch as the unittests won't be
built anymore

We can also finely tune options such as gflags, threads and dynamic
library support. This last option is handled through the standard
BUILD_SHARED_LIBS option

Fixes:
 - http://autobuild.buildroot.net/results/5a659d960c24256a2905f129dfa70e3dc9e92aec

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>