Log Message:
php7*: Standardise on major.minor.99 usage in buildlink3.mk

With the introduction of beta and rc releases of php7* into pkgsrc the pattern
matching is often incorrect (for example the current version of php-7.1.0rc6
breaks both <7.1.0 and >=7.1.0).  Using .99 is not ideal but does at least
avoid the confusion developers seem to be having with the pmatch ordering.