1) fix_tools_exports.pl need only be run on Windows hosts; was run unnecessarily on Linux too.
2) Need to export modload.pm on Linux as well as Windows hosts.
# B2.var
EXTENDS A2
VARIANT B2
BUILD_INCLUDE append /epoc32/include/B1/build
BUILD_INCLUDE prepend /prepend/include/B1
ROM_INCLUDE prepend /epoc32/include/B1/rom