When LLVM is embedded in a larger application, it's not OK for LLVM to intercept crashes.  LLVM already has 
the ability to disable this functionality.  This patch exposes it via the C API.

llvm-svn: 193937
diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index 690ffa9f..47d566c 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -434,6 +434,12 @@
 void LLVMResetFatalErrorHandler(void);
 
 /**
+ * Disable LLVM's built-in stack trace code. This must be called before any
+ * other LLVM APIs; otherwise the results are undefined.
+ */
+void LLVMDisablePrettyStackTrace(void);
+
+/**
  * @defgroup LLVMCCoreContext Contexts
  *
  * Contexts are execution states for the core LLVM IR system.