tools/coverage.sh: Expand bash aliases and source bash profile

This way the script also works if you have 'bazel' alias that points to
'bazelisk'.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I150d4972fb62f0249ffa577333a26a474a0a5855
diff --git a/tools/coverage.sh b/tools/coverage.sh
index 3582d22..e03ac7f 100755
--- a/tools/coverage.sh
+++ b/tools/coverage.sh
@@ -7,6 +7,9 @@
 # COVERAGE_CPUS defaults to 2, and the default destination is a temp
 # dir.
 
+shopt -s expand_aliases
+source ~/.bash_profile
+
 genhtml=$(which genhtml)
 if [[ -z "${genhtml}" ]]; then
     echo "Install 'genhtml' (contained in the 'lcov' package)"