testsuite: fix scan-tree-dump patterns [PR83904,PR100297]

Adjust scan-tree-dump patterns so that they do not accidentally match a
valid path.

gcc/testsuite/ChangeLog:

	PR testsuite/83904
	PR fortran/100297
	* gfortran.dg/allocatable_function_1.f90: Use "__builtin_free "
	instead of the naive "free".
	* gfortran.dg/reshape_8.f90: Extend pattern from a simple "data".