databases/rrdtool: Fix build with PYTHON option on

• Add py-setuptools build dependency to PYTHON option (Build PYTHON bindings) to fix build when this option is used
• Add harfbuzz lib depends to GRAPH option (Enable the rrdtool graph command)
• Use configure helper for EXAMPLES option
• Define LICENSE_FILE

PR: 265203
Reported by: Sigi <freebsd-bt@beatsnet.com>
MFH: 2023Q1 (build fixes)