Don't even dare check for Fortran

...which can lead to problems when e.g. building against a local trunk GCC
(requiring LD_LIBRARY_PATH) that was configured to build only C/C++ compilers,
so CoinMP's configuration would try to blend that with the system's gfortran.

Change-Id: I9f237df0887e06e50b9e76f3a09cfebb6f22dc20

external/coinmp/ExternalProject_coinmp.mk

@@ -27,7 +27,7 @@ else
 $(call gb_ExternalProject_get_state_target,coinmp,build) :
 	+$(call gb_ExternalProject_run,build,\
 		./configure COIN_SKIP_PROJECTS="Data/Sample" \
-			--enable-dependency-linking \
+			--enable-dependency-linking F77=unavailable \
 		&& $(MAKE) \
 	)