Auto merge of #690 - KyleMayes:clang-sys, r=fitzgen

Bump clang-sys to 0.17.0

It turns out that some versions of Clang don't have `#include <...> search starts here:` in their output (KyleMayes/clang-sys#54).

I changed the storage type of the include search paths in `clang-sys` from `Vec<PathBuf>` to `Option<Vec<PathBuf>>` to reflect the possibility that finding and parsing the include search paths might fail.

Author: bors-servo

Cargo.lock

@@ -44,7 +44,7 @@ quasi_codegen = "0.32"
 [dependencies]
 cexpr = "0.2"
 cfg-if = "0.1.0"
-clang-sys = { version = "0.16.0", features = ["runtime", "clang_3_9"] }
+clang-sys = { version = "0.17.0", features = ["runtime", "clang_3_9"] }
 lazy_static = "0.2.1"
 syntex_syntax = "0.58"
 regex = "0.2"

Cargo.toml

@@ -1047,10 +1047,12 @@ impl<'ctx> Bindings<'ctx> {
             if !has_target_arg {
                 // TODO: distinguish C and C++ paths? C++'s should be enough, I
                 // guess.
-                for path in clang.cpp_search_paths.into_iter() {
-                    if let Ok(path) = path.into_os_string().into_string() {
-                        options.clang_args.push("-isystem".to_owned());
-                        options.clang_args.push(path);
+                if let Some(cpp_search_paths) = clang.cpp_search_paths {
+                    for path in cpp_search_paths.into_iter() {
+                        if let Ok(path) = path.into_os_string().into_string() {
+                            options.clang_args.push("-isystem".to_owned());
+                            options.clang_args.push(path);
+                        }
                     }
                 }
             }