[XRay] Reduce overly broad 'rm' command in lit test

[jmorse]

Summary

This command is supposed to clean up temporary log files from this
test, but winds up cleaning all xray log files in the cwd, which can
interfere with other test processes.

We've seen this internally as errors such as:

rm: cannot remove 'xray-log.c-test.cc.tmp.bFiBJc': No such file or directory

Where the shell has globbed the logfile for a different test (c-test.cc here)
but a concurrent test process has deleted it by the time rm gets to running.

[dberris]

LGTM -- Thanks!

[jmorse]

Fixed concurrently by r343282!

[MaskRay]

In D52599#1248882, @jmorse wrote:

Fixed concurrently by r343282!

:)

I missed another race in the description. There are two:

• rm can delete files of other tests and cause them to fail
• shell may expand file names first but when rm tries deleting them, other tests have already deleted the files and cause the test to fail.

llvm/projects/compiler-rt/test/xray/TestCases/Posix/argv0-log-file-name.cc

 // Check to make sure argv[0] is contained within the (randomised) XRay log file
 // name.
 
 // RUN: %clangxx_xray -std=c++11 %s -o %t
 // RUN: XRAY_OPTIONS="patch_premain=true xray_naive_log=true" %run %t > xray.log.file.name 2>&1
 // RUN: ls | FileCheck xray.log.file.name
-// RUN: rm xray-log.* xray.log.file.name
+// RUN: rm xray-log.argv0-log-file-name* xray.log.file.name
 
 // UNSUPPORTED: target-is-mips64,target-is-mips64el
 
 #include <cstdio>
 #include <libgen.h>
 
 [[clang::xray_always_instrument]] int main(int argc, char *argv[]) {
   printf("// CHECK: xray-log.%s.{{.*}}\n", basename(argv[0]));
 }