auto merge of #5317 : luqmana/rust/inline-asm, r=graydon

```Rust
#[cfg(target_os = "macos")]
fn helloworld() {
    unsafe {
        asm!(".pushsection __RODATA, __rodata
                  msg: .asciz \"Hello World!\"
              .popsection
              movq msg@GOTPCREL(%rip), %rdi
              call _puts");
    }
}

#[cfg(target_os = "linux")]
fn helloworld() {
    unsafe {
        asm!(".pushsection .rodata
                  msg: .asciz \"Hello World!\"
              .popsection
              movq msg@GOTPCREL(%rip), %rdi
              call puts");
    }
}

fn main() {
    helloworld();
}
```

```
% rustc foo.rs
% ./foo
Hello World!
```

1 files changed, 12 insertions, 0 deletions

diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 3af936d3461..7686dcd4ff4 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -15,6 +15,7 @@
 //
 //===----------------------------------------------------------------------===
 
+#include "llvm/InlineAsm.h"
 #include "llvm/LLVMContext.h"
 #include "llvm/Linker.h"
 #include "llvm/PassManager.h"
@@ -539,3 +540,14 @@ extern "C" void LLVMSetDebug(int Enabled) {
   DebugFlag = Enabled;
 #endif
 }
+
+extern "C" LLVMValueRef LLVMInlineAsm(LLVMTypeRef Ty,
+                                      char *AsmString,
+                                      char *Constraints,
+                                      LLVMBool HasSideEffects,
+                                      LLVMBool IsAlignStack,
+                                      InlineAsm::AsmDialect Dialect) {
+    return wrap(InlineAsm::get(unwrap<FunctionType>(Ty), AsmString,
+                               Constraints, HasSideEffects,
+                               IsAlignStack, Dialect));
+}