Update version number in the README
We need at least automake 1.11.4 to provide the necessary config.guess and config.sub for aarch64

This reverts commit 1a18abd94084b887997d8d2133f337a39cced266.
Require autoconf 2.69 to support aarch64
Bump version to 1.5.2
Add exec_prefix to geoip.pc.in
Add region code TH81 Bueng Kan
bootstrap download the dat file if needed
Updated README.md version