Add clang_getDiagnosticSetFromTU() to libclang.  Fixes <rdar://problem/10553081>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146287 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/libclang.exports b/tools/libclang/libclang.exports
index 5d37b59..b028bb4 100644
--- a/tools/libclang/libclang.exports
+++ b/tools/libclang/libclang.exports
@@ -97,6 +97,7 @@
 clang_getDiagnosticNumRanges
 clang_getDiagnosticOption
 clang_getDiagnosticRange
+clang_getDiagnosticSetFromTU
 clang_getDiagnosticSeverity
 clang_getDiagnosticSpelling
 clang_getElementType