Fix LLVM 3.0 build issue.

LLVM 3.0's raw_fd_ostream doesn't take an std::string as file name.

Bug swiftshader:123
Bug b/123193054

Change-Id: I994f6fe5ce98c573d4be48737934b7c6c0127434
Reviewed-on: https://swiftshader-review.googlesource.com/c/24088
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/Reactor/LLVMReactor.cpp

diff --git a/src/Reactor/LLVMReactor.cpp b/src/Reactor/LLVMReactor.cpp
index 344fe52..6c8d9c6 100644
--- a/src/Reactor/LLVMReactor.cpp
+++ b/src/Reactor/LLVMReactor.cpp
@@ -906,12 +906,14 @@
 
 		if(false)
 		{
-#if REACTOR_LLVM_VERSION < 7
-			std::string error;
-#else
-			std::error_code error;
-#endif
-			llvm::raw_fd_ostream file(std::string(name) + "-llvm-dump-unopt.txt", error);
+			#if REACTOR_LLVM_VERSION < 7
+				std::string error;
+				llvm::raw_fd_ostream file((std::string(name) + "-llvm-dump-unopt.txt").c_str(), error);
+			#else
+				std::error_code error;
+				llvm::raw_fd_ostream file(std::string(name) + "-llvm-dump-unopt.txt", error);
+			#endif
+
 			::module->print(file, 0);
 		}
 
@@ -922,12 +924,14 @@
 
 		if(false)
 		{
-#if REACTOR_LLVM_VERSION < 7
-			std::string error;
-#else
-			std::error_code error;
-#endif
-			llvm::raw_fd_ostream file(std::string(name) + "-llvm-dump-opt.txt", error);
+			#if REACTOR_LLVM_VERSION < 7
+				std::string error;
+				llvm::raw_fd_ostream file((std::string(name) + "-llvm-dump-opt.txt").c_str(), error);
+			#else
+				std::error_code error;
+				llvm::raw_fd_ostream file(std::string(name) + "-llvm-dump-opt.txt", error);
+			#endif
+
 			::module->print(file, 0);
 		}