Rollup merge of rust-lang#36784 - jonathandturner:env_var, r=alexcrichton

Remove requirement to use 10.7 (fixes macOS)

Fixes rust-lang#36650 by removing the requirement to use 10.7.  @alexcrichton pointed out that the buildbots won't be affected, since they set the requirement with an environment variable.

This should now allow rustbuild to build Rust on macOS (nee OS X)

r? @alexcrichton

Author: Jonathan Turner

src/bootstrap/lib.rs

@@ -659,12 +659,6 @@ impl Build {
                  .env(format!("CFLAGS_{}", target), self.cflags(target).join(" "));
         }
 
-        // If we're building for OSX, inform the compiler and the linker that
-        // we want to build a compiler runnable on 10.7
-        if target.contains("apple-darwin") {
-            cargo.env("MACOSX_DEPLOYMENT_TARGET", "10.7");
-        }
-
         // Environment variables *required* needed throughout the build
         //
         // FIXME: should update code to not require this env var
@@ -933,7 +927,6 @@ impl Build {
         // LLVM/jemalloc/etc are all properly compiled.
         if target.contains("apple-darwin") {
             base.push("-stdlib=libc++".into());
-            base.push("-mmacosx-version-min=10.7".into());
         }
         // This is a hack, because newer binutils broke things on some vms/distros
         // (i.e., linking against unknown relocs disabled by the following flag)