testsuite: Remove reliance on argc in lto/pr101868_0.c
Some embedded targets do not pass any argv arguments. When argc is
zero, this causes spurious failures for lto/pr101868_0.c. Fix by
following the strategy in r0-114701-g2c49569ecea56d. Use a volatile
variable instead of argc to inject a runtime value into the test.
I validated the following:
- No changes in testresults for x86_64-pc-linux-gnu.
- The spurious failures are fixed for PRU target.
- lto/pr101868_0.c still fails on x86_64-pc-linux-gnu, if
the PR/101868 fix (r12-2254-gfedcf3c476aff7) is reverted.
PR tree-optimization/101868
gcc/testsuite/ChangeLog:
* gcc.dg/lto/pr101868_0.c (zero): New volatile variable.
(main): Use it instead of argc.
Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>