*: strip calls to cc::Build::compile

The documentation states: "The name output should be the name of the
library." and this is already done in more recently-added callers.

src/bootstrap/native.rs

@@ -316,7 +316,7 @@ impl Step for TestHelpers {
            .warnings(false)
            .debug(false)
            .file(build.src.join("src/rt/rust_test_helpers.c"))
-           .compile("librust_test_helpers.a");
+           .compile("rust_test_helpers");
     }
 }
 

src/liballoc_jemalloc/build.rs

@@ -140,6 +140,6 @@ fn main() {
         cc::Build::new()
             .flag("-fvisibility=hidden")
             .file("pthread_atfork_dummy.c")
-            .compile("libpthread_atfork_dummy.a");
+            .compile("pthread_atfork_dummy");
     }
 }

src/libprofiler_builtins/build.rs

@@ -56,5 +56,5 @@ fn main() {
         cfg.file(Path::new("../libcompiler_builtins/compiler-rt/lib/profile").join(src));
     }
 
-    cfg.compile("libprofiler-rt.a");
+    cfg.compile("profiler-rt");
 }

src/librustc_llvm/build.rs

@@ -169,7 +169,7 @@ fn main() {
        .file("../rustllvm/ArchiveWrapper.cpp")
        .cpp(true)
        .cpp_link_stdlib(None) // we handle this below
-       .compile("librustllvm.a");
+       .compile("rustllvm");
 
     let (llvm_kind, llvm_link_arg) = detect_llvm_link(major, minor, &llvm_config);
 

src/librustdoc/build.rs

@@ -27,6 +27,6 @@ fn main() {
        .warnings(false)
        .include(src_dir)
        .warnings(false)
-       .compile("libhoedown.a");
+       .compile("hoedown");
 }