Mark buildFromIterator test as conflicting

Commit 0b2e6bc started caching the directory entry type to improve
performance. Shortly after, we've seen flaky failures of the
buildFromIterator phar test.

When it fails, it's always a value error in the constructor of
RecursiveDirectoryIterator::__construct() with a "no such file or
directory" error. What's happening here is this:
1) A parallel test creates a subdirectory in the current working dir.
2) This test checks hasChildren() on a directory entry, the cached entry
   returns "yes" on the subdirectory.
3) The parallel test finishes and removes the subdirectory.
4) The constructor mentioned above is called, causing an exception
   because the directory is gone.

This race has always been possible, even before said commit. It's just
that it was very hard to hit before: the expensive stat call made the
race window hard to hit. The race is now easier to hit because of the
caching that is fast.

Since there's many tests that modify the current working directory, it
seems best to mark this as an "all" conflict. We cannot avoid every
TOC-TOU race when working with files with these phar tests.

In particular, mounteddir.phpt caused every conflict I saw on CI, but
there's more tests that create subdirectories in the current working
directory.

Closes GH-11869.

Author: nielsdos

ext/phar/tests/phar_buildfromiterator10.phpt

@@ -2,6 +2,8 @@
 Phar::buildFromIterator() RegexIterator(RecursiveIteratorIterator), SplFileInfo as current
 --EXTENSIONS--
 phar
+--CONFLICTS--
+all
 --INI--
 phar.require_hash=0
 phar.readonly=0