fortran: [PR126210] Restrict host-assoc symbol skip to derived types

The fix for PR126170 made read_module() skip re-importing any
symbol already visible via host association from the same
module, matched only by name.

	PR fortran/126210

gcc/fortran/ChangeLog:

	* module.cc (read_module): Only skip re-importing a symbol
	already visible via host association from the same module
	when that symbol is a derived type.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pr126210.f90: New test.

(cherry picked from commit 69a2daacba6353d1aab3118415b89afd479c4c76)