Make Travis build deps in parallel again

revert unnecessary change from https://github.com/JuliaLang/julia/pull/19475/files#r93611089
which causes linux builds from a clean cache to time out (and build
llvm twice, once with assertions and once without) but was not noticed
when building from an already-populated cache

.travis.yml

@@ -102,7 +102,7 @@ script:
     # capture the log, but only print it if `make deps` fails
     # try to show the end of the log first, because this log might be very long (> 4MB)
     # and thus be truncated by travis
-    - moreutils/mispipe "make \$BUILDOPTS VERBOSE=0 -C deps 2> deps-err.log" "$BAR" > deps.log ||
+    - moreutils/mispipe "make $BUILDOPTS VERBOSE=0 -C deps 2> deps-err.log" "$BAR" > deps.log ||
         { echo "-- deps build log stderr tail 100 --------------------------------------";
           tail -n 100 deps-err.log;
           echo "-- deps build log stdout tail 100 --------------------------------------";