pi_http: update pi_framework_mod.xsl to generate new pi_http samples
 - add link_cmd to the primary key for DB_UPDATE commands
(cherry picked from commit d0ced797fce24c00502a008ab12e88eeeea85b0f)
pi_http: samples regenerated
(cherry picked from commit cbf2f118c407aa6549cce43fc6e9b6bcf9ae09fc)