Preprocessor: Ignore unknown pragmas in -E -dM and -Eonly modes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@105830 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Frontend/unknown-pragmas.c b/test/Frontend/unknown-pragmas.c
new file mode 100644
index 0000000..53a5a45
--- /dev/null
+++ b/test/Frontend/unknown-pragmas.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -Eonly -Wall -verify %s
+// RUN: %clang_cc1 -E -dM -Wall -verify %s
+
+#pragma adgohweopihweotnwet