Remove note from the top of environment.in. It's obsolete.
Fix Guile compiled path in environment.in

Compiled files go to prefix/lib/guile/2.0/ccache, which isn't the same as
where the source files are stored (prefix/share/guile/2.0), so provide a
separate variable for it. Also don't throw away the user's value of
GUILE_LOAD_COMPILED_PATH in favor of GUILE_LOAD_PATH.
Bug 739584 - gnucash-2.6.4 segfaults regularly on transfer .

Ensure that xferData is nulled after free and that client functions check
for the NULL.
Adjust #ifdef __clang__ to exclude clang versions > 6

This works only with Apple clang; the regular clang is at version 3, but
hasn't been tested for what versions emit what sort of function signatures
to logs.
Replace GNC_HOME/bin with gnc_path_get_bindir().

For consistency with the rest of the function.