build: Fix getting available memory on mac

build/toolchain/get_concurrent_links.py

Index: build/toolchain/get_concurrent_links.py
diff --git a/build/toolchain/get_concurrent_links.py b/build/toolchain/get_concurrent_links.py
index e957de64bfd5689fada2f714c1a0524a8c5f4b6d..7765d9ecabe1bafed8bf682fb06c567c9e6ef8c3 100644
--- a/build/toolchain/get_concurrent_links.py
+++ b/build/toolchain/get_concurrent_links.py
@@ -42,7 +42,7 @@ def _GetTotalMemoryInBytes():
           return float(match.group(1)) * 2**10
   elif sys.platform == 'darwin':
     try:
-      avail_bytes = int(subprocess.check_output(['sysctl', '-n', 'hw.memsize']))
+      return int(subprocess.check_output(['sysctl', '-n', 'hw.memsize']))
     except Exception:
       return 0
   # TODO(scottmg): Implement this for other platforms.