[Fortran/gfortran] Disable test not supported on AArch64.

The test requires the `dg-require-effective-target fortran_real_10` directive
to be handled correctly which is not currently done. Disable the test for now
so the buildbots don't fail.

Differential Revision: https://reviews.llvm.org/D154878

Author: tarunprabhu

Fortran/gfortran/regression/DisabledFiles.cmake

@@ -1969,6 +1969,12 @@ file(GLOB SKIPPED_FILES CONFIGURE_DEPENDS
   goto_5.f90
   pr49540-1.f90 # Only on AArch64
 
+  # --------------------------------------------------------------------------
+  #
+  # These tests are skipped because REAL(10) is not supported on AAch64.
+
+  pr91497.f90
+
   # --------------------------------------------------------------------------
   #
   # These are skipped almost certainly because of a bug in the way multi-file