Check in forgotten test for fortran/65766

From-SVN: r228564

gcc/testsuite/gfortran.dg/substr_alloc_string_comp_1.f90

+! { dg-do run }
+! PR fortran/65766
+! Substrings of allocatable string components of derived types
+program substr_derived_alloc_comp
+    implicit none
+
+    type t1
+        character(len=:), allocatable :: s
+    end type t1
+
+    character(len=*), parameter :: c = &
+      "0123456789abcdefghijklmnopqrstuvwxyz"
+
+    type(t1) x1
+
+    integer i
+
+    x1%s = c
+
+    do i = 1, 36
+        if (x1%s(i:) .ne. c(i:)) call abort
+    end do
+end program