Don't put a trailing dot in set_package_properties

It looks weird given the kind of visualization where this text is
displayed.

Bad:

 * XKB (required version >= 0.5.0), XKB API common to servers and clients., <http://xkbcommon.org>

Good:

 * XKB (required version >= 0.5.0), XKB API common to servers and clients, <http://xkbcommon.org>

cmake/modules/FindLibdrm.cmake

@@ -101,5 +101,5 @@ endif()
 include(FeatureSummary)
 set_package_properties(Libdrm PROPERTIES
     URL "https://wiki.freedesktop.org/dri/"
-    DESCRIPTION "Userspace interface to kernel DRM services."
+    DESCRIPTION "Userspace interface to kernel DRM services"
 )

cmake/modules/FindXKB.cmake

@@ -85,5 +85,5 @@ endif()
 include(FeatureSummary)
 set_package_properties(XKB PROPERTIES
     URL "https://xkbcommon.org"
-    DESCRIPTION "XKB API common to servers and clients."
+    DESCRIPTION "XKB API common to servers and clients"
 )

cmake/modules/Findgbm.cmake

@@ -100,5 +100,5 @@ endif()
 include(FeatureSummary)
 set_package_properties(gbm PROPERTIES
     URL "https://www.mesa3d.org"
-    DESCRIPTION "Mesa gbm library."
+    DESCRIPTION "Mesa gbm library"
 )