radeon: bump libdrm_radeon requirement for CIK support

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

configure.ac

@@ -31,7 +31,7 @@ AC_SUBST([OSMESA_VERSION])
 
 dnl Versions for external dependencies
 LIBDRM_REQUIRED=2.4.24
-LIBDRM_RADEON_REQUIRED=2.4.45
+LIBDRM_RADEON_REQUIRED=2.4.46
 LIBDRM_INTEL_REQUIRED=2.4.38
 LIBDRM_NVVIEUX_REQUIRED=2.4.33
 LIBDRM_NOUVEAU_REQUIRED="2.4.33 libdrm >= 2.4.41"