compile.sh: Use emar in order to bundle libraries.
compile.sh: Use emar in order to bundle libraries.

This is necessary in order to use emscripten's new compiler, as
described here:
https://bit.ly/2ZlwQmz

Change-Id: I66e0a6e4e403b7a9ba94860ea9cc7e53027d6f46
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/237396
Reviewed-by: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia