Fix open_pdb_file (used for locate/open pdbs):
- pdb_match heuristic now only stop when "first file" exists
- SymFindFileInPath now fill output buffer with a valid value on
  success.

diff --git a/dlls/dbghelp/path.c b/dlls/dbghelp/path.c
index dac09ba..7358047 100644
--- a/dlls/dbghelp/path.c
+++ b/dlls/dbghelp/path.c
@@ -342,7 +342,10 @@
             strcpy(tmp, searchPath);
             searchPath = NULL;
         }
-        if (do_search(filename, tmp, FALSE, sffip_cb, &s)) return TRUE;
+        if (do_search(filename, tmp, FALSE, sffip_cb, &s)) {
+            strcpy(buffer, tmp);
+            return TRUE;
+        }
     }
     return FALSE;
 }