libpcp_web: small memory leak fix found by valgrind in qa
libpcp_web: small memory leak fix found by valgrind in qa

Re-use the passed-in value string, else we leak extracting values.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp