Fix mingw targets. Bandaid for r252532's buildbot brakage.

Reviewers: brad.king, beanz

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14523

llvm-svn: 252576
diff --git a/llvm/tools/llvm-config/llvm-config.cpp b/llvm/tools/llvm-config/llvm-config.cpp
index f6d55b4..c47f437 100644
--- a/llvm/tools/llvm-config/llvm-config.cpp
+++ b/llvm/tools/llvm-config/llvm-config.cpp
@@ -333,7 +333,7 @@
     StaticExt = "a";
     SharedDir = ActiveBinDir;
     StaticDir = ActiveLibDir;
-    StaticPrefix = SharedPrefix = "";
+    StaticPrefix = SharedPrefix = "lib";
   } else if (HostTriple.isOSDarwin()) {
     SharedExt = "dylib";
     SharedVersionedExt = PACKAGE_VERSION ".dylib";