Fix create_proxy! macro

[termoshtt]

error: unexpected end of macro invocation
  --> /home/travis/build/denzp/rustc-llvm-proxy/target/debug/build/rustc-llvm-proxy-8a4ff3d82bd298fa/out/llvm_gen.rs:6:152
   |
6  | create_proxy!(LLVMContextSetDiagnosticHandler; (); C : LLVMContextRef , Handler : LLVMDiagnosticHandler , DiagnosticContext : * mut :: libc :: c_void ,);
   |                                                                                                                                                        ^ missing tokens in macro arguments
   | 
  ::: src/lib.rs:93:5
   |
93 |     macro_rules! create_proxy {
   |     ------------------------- when calling this macro

https://travis-ci.org/denzp/rustc-llvm-proxy/jobs/625547316

This patch fix it by removing , at the end

[denzp]

Thank you, LGTM!

[denzp]

I'll try to revive #7 to pass tests on linux and osx and then publish to Crates.

[denzp]

Oh, scrap the last message: I've published v0.1.11 with the changes!

[denzp]

Also, the v0.2.0 is out - it uses libLLVM that can be found on Linux and MacOS and it's generally more reliable approach. Unfortunately, both v0.1 and v0.2 are broken on Windows.