modules/common: added hdlmake Manifest.

modules/common/Manifest.py

+files = [	"gencores_pkg.vhd",
+					"gc_crc_gen.vhd",
+					"gc_moving_average.vhd",
+					"gc_extend_pulse.vhd",
+					"gc_delay_gen.vhd",
+					"gc_dual_pi_controller.vhd",
+					"gc_serial_dac.vhd",
+					"gc_sync_ffs.vhd"];