[dsymutil] Replace PATH_MAX in SmallString with fixed value.
[dsymutil] Replace PATH_MAX in SmallString with fixed value.

Apparently the Windows bots don't know this define, so just going with a
sensible default.

Failing builds:
  http://lab.llvm.org:8011/builders/lldb-x86-windows-msvc2015/builds/19179
  http://lab.llvm.org:8011/builders/lld-x86_64-win7/builds/19263

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@325762 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 612ed3c0007b15a8f82fb3cf3b5f1052384e726a)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm