Fix typo in comment in script `tools/buildbot-build.sh`.

Test: n/a (comment-only change)
Change-Id: I5232ef1674fffd5114170297e0b752fe77a63fae
diff --git a/tools/buildbot-build.sh b/tools/buildbot-build.sh
index 4af36c5..7692fa7 100755
--- a/tools/buildbot-build.sh
+++ b/tools/buildbot-build.sh
@@ -181,7 +181,7 @@
     fi
   done
 
-  # Replace stub libraries with implemenation libraries: because we do chroot
+  # Replace stub libraries with implementation libraries: because we do chroot
   # testing, we need to install an implementation of the libraries (and cannot
   # rely on the one already installed on the device, if the device is post R and
   # has it).