Fix build on Solaris 11.

Patch by Vladimir Voskresensky. The erros were:

Path.inc:274:3: error: ‘Dl_info’ was not declared in this scope
...

and

usr/include/spawn.h:52:14: error: expected ‘,’ or ‘...’ before ‘argv’

llvm-svn: 192185
diff --git a/llvm/lib/Support/Unix/Unix.h b/llvm/lib/Support/Unix/Unix.h
index dd11c04..ba688e3 100644
--- a/llvm/lib/Support/Unix/Unix.h
+++ b/llvm/lib/Support/Unix/Unix.h
@@ -47,6 +47,10 @@
 # include <sys/wait.h>
 #endif
 
+#ifdef HAVE_DLFCN_H
+# include <dlfcn.h>
+#endif
+
 #ifndef WEXITSTATUS
 # define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
 #endif