CPPAN=1, CPPAN_BUILD=1 - defined when sources are compiled under CPPAN build.

CPPAN_EXPORT - automatically set to proper export/import definition when building shared library on any platform.

CPPAN_CONFIG - string with current compiler configuration. For example, "amd64-msvc-19.0-32", "armv7-a-gnu-4.9-32".