Uses/cmake.mk: Replace CMAKE_ENV with CONFIGURE_ENV.

[rakuco]

Summary

Instead of defining a variable that is almost always based on CONFIGURE_ENV, just use CONFIGURE_ENV directly. This also matches the behavior of other ports that do not use autotools (so most ports can just worry about CONFIGURE_ENV). Additionally, the fact that we do not use ?= means we do not have problems if another file in Uses/ needs to set CONFIGURE_ENV (with CMAKE_ENV, the order of the arguments to USES would matter).

Test Plan

All mentioned ports have been tested with the change and build fine on 9.3-i386.

[makc]

math/eigen3/Makefile

17 ↗

(On Diff #8015)

LOCALBASE is incorrectly used here instead of PREFIX

[rakuco]

math/eigen3/Makefile

17 ↗

(On Diff #8015)

Fixed in rP394563.