In the installation whose prefix is other than /usr/local,
osxfuse library and include path must explicitly be specified during build.
Although brew's pkg-config is configured to prepend appropriates paths,
the prepended paths (/usr/local) supercede the original HOMEBREW_PREFIX.
This behavior will cause the linker to select libraries outside brew's tree.
By adding /usr/local to HOMEBREW_LIBRARY_PATHS, superenv ensures that appears
only after the HOMEBREW_PREFIX, and thus fixes this problem.
HOMEBREW_INCLUDE_PATHS is also configured like keg-only Formulae.
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