liblogcat: -v and ${ANDROID_PRINTF_LOG} support comma separated list

Deal with yet another reentrancy issue with strtok() and do not
treat optarg as fungible data, allocate a temporary copy.  Add
support in the -v flag and environmental variable ANDROID_PRINTF_LOG
for a comma-separated list of format and format modifiers.

Test: manual + gTest logcat-unit-tests
Bug: 35326290
Change-Id: I073e5676d59ba41bfd36df86942342766ef730f1