Makefile: Use Bash as Make shell

The default is /bin/sh which can differ among individual workstations.
Explicitly pick Bash to avoid compatibility issues and allow using its
non-POSIX features.

Bug: 193407077
Test: make test
Change-Id: I6832c3e5da774d98952ff82c13c95cb320b7ae8f
1 file changed
tree: d76c21cca5fe1177b90f5b9167c9da3435ffaee3
  1. aarch64/
  2. crosvm/
  3. cuttlefish/
  4. kvm-unit-tests/
  5. common.inc
  6. Makefile