gcc.dg/torture/pr39074-2.c, pr39074.c, pta-callused-1.c: Adjust for mmix.

gcc.dg/torture/pr39074-2.c, pr39074.c, pta-callused-1.c: Adjust for mmix.

These FAILs for mmix showed up as regressions for me due to a
flaw in the btest-gcc.sh test-results-accounting: a bug was
recently fixed regarding the naming of dump-files so the names
are again correct.  To wit, parts of the tests that were
UNRESOLVED, due to missing dump-files, and ignored in the
presence of other parts (execution, excess errors) PASSing,
became FAIL, trumping the PASSing parts of the tests.

As in a recent patch, the variables are "privatized" using
ASM_PN_FORMAT for MMIX and the lines to match look like:
 y::0_1 = { i }
 y::0_1, points-to NULL, points-to vars: { D.1465 } (nonlocal, escaped)
instead of e.g. for cris-elf:
 y.0_1 = { i }
 y.0_1, points-to NULL, points-to vars: { D.1433 } (nonlocal, escaped)
Also checked that the general pattern still matches for cris-elf.

gcc/testsuite:
	* gcc.dg/torture/pr39074-2.c: Adjust for mmix.
	* gcc.dg/torture/pr39074.c, gcc.dg/torture/pta-callused-1.c: Ditto.