Revert "Explicit use base::Location stack/btu/btu_hcif::"

Revert submission 1512835

Reason for revert: DroidMonitor-triggered revert due to breakages:

https://android-build.googleplex.com/builds/quarterdeck?branch=aosp-master&target=aosp_cf_x86_phone-userdebug&lkgb=7002541&lkbb=7002623&fkbb=7002623
https://android-build.googleplex.com/builds/quarterdeck?branch=aosp-master&target=sdk_x86_64-sdk&lkgb=7002541&lkbb=7002623&fkbb=7002623
https://android-build.googleplex.com/builds/quarterdeck?branch=aosp-master&target=full-eng&lkgb=7002541&lkbb=7002623&fkbb=7002623
https://android-build.googleplex.com/builds/quarterdeck?branch=aosp-master&target=aosp_cf_x86_64_phone-userdebug&lkgb=7002434&lkbb=7002649&fkbb=7002649
https://android-build.googleplex.com/builds/quarterdeck?branch=git_rvc-d1-dev-plus-aosp&target=aosp_cf_x86_phone-userdebug&lkgb=7002643&lkbb=7002696&fkbb=7002696
https://android-build.googleplex.com/builds/quarterdeck?branch=git_rvc-d1-dev-plus-aosp&target=docs&lkgb=7002604&lkbb=7002703&fkbb=7002696


bug http://b/174517408
Reverted Changes:
Ieb002c783:Canonicalize include files
I69d5dff4f:enum-ify fixed_cid stack/include/l2cdefs::L2CAP_
I5a52498ad:Introduce net_test_stack_btm
I6a637b5e2:Explicit use base::Location stack/btu/btu_hcif::
I23c831a61:Add various stack/test/common/mock_

Change-Id: I7d8eb39fde70160b1a3dbb0e47e1b36806023543