travis: Get an emscripten builder online

This commit adds a new entry to the Travis matrix which will execute emscripten
test suites. Along the way it updates a few bits of the test suite to continue
passing on emscripten, such as:

* Ignoring i128/u128 tests as they're presumably just not working (didn't
  investigate as to why)
* Disabling a few process tests (not working on emscripten)
* Ignore some num tests in libstd (#39119)
* Fix some warnings when compiling

1 files changed, 1 insertions, 1 deletions

diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 66bdd5e00f4..8e79c2d27d1 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -45,7 +45,7 @@ pub fn check(build: &mut Build) {
             let target = path.join(cmd);
             let mut cmd_alt = cmd.to_os_string();
             cmd_alt.push(".exe");
-            if target.exists() ||
+            if target.is_file() ||
                target.with_extension("exe").exists() ||
                target.join(cmd_alt).exists() {
                 return Some(target);