[Support] Support building LLVM for Fuchsia

These are necessary changes to support building LLVM for Fuchsia.
While these are not sufficient to run on Fuchsia, they are still
useful when cross-compiling LLVM libraries and runtimes for Fuchsia.

Differential Revision: https://reviews.llvm.org/D46345

llvm-svn: 331423
diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 9bd8cca..f977832 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -365,6 +365,9 @@
 #elif defined(__CYGWIN__)
   // Cygwin doesn't expose this information; would need to use Win32 API.
   return false;
+#elif defined(__Fuchsia__)
+  // Fuchsia doesn't yet support remote filesystem mounts.
+  return true;
 #elif defined(__sun)
   // statvfs::f_basetype contains a null-terminated FSType name of the mounted target
   StringRef fstype(Vfs.f_basetype);