modernize num_def (trivial)

Author: pmocz

num/make/makefile_base

@@ -13,7 +13,7 @@ include $(MESA_DIR)/utils/makefile_header
 # SOURCE FILES
 
 SRCS = \
-   num_def.f \
+   num_def.f90 \
    mod_dop853.f mod_dopri5.f mod_dc_decsol.f \
    mod_rosenbrock.f mod_brent.f90 mod_qsort.f90 mod_root.f mod_solout_root.f \
    mod_random.f90 mod_newton.f mod_bobyqa.f mod_newuoa.f \