gstlal_simulation.c: add missing header files

- the header files in the lalinspiral are a total mess, and as I clean them
  up I'm discovering other codes that have been omitting some headers
  because they were being pulled in from lalinspiral files.  this probably
  won't be the last time I have to adjust things before the dust settles.

gstlal/gst/lal/gstlal_simulation.c

@@ -46,6 +46,7 @@
  */
 
 
+#include <math.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -71,12 +72,14 @@
 #include <lal/GenerateBurst.h>
 #include <lal/LALConfig.h>
 #include <lal/LALDatatypes.h>
+#include <lal/LALInspiral.h>
 #include <lal/LALSimInspiral.h>
 #include <lal/LALSimulation.h>
 #include <lal/LALStdlib.h>
 #include <lal/LIGOLwXML.h>
 #include <lal/LIGOMetadataTables.h>
 #include <lal/LIGOMetadataUtils.h>
+#include <lal/LIGOMetadataInspiralUtils.h>
 #include <lal/SnglBurstUtils.h>
 #include <lal/TimeSeries.h>
 #include <lal/Units.h>