Improve guile testing in configure.ac

Use guile specific macros to determing the guile executable to use.
Unfortunately the macro names may be different on various supported
platforms. So we have to run some extra tests to determine which
macro names we need exactly.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23390 57a11ea4-9604-0410-9ed3-97b8803252fd
Replace all uses of GUILE_INCS with GUILE_CFLAGS

This cleans up some left overs from before guile had a .pc file

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23391 57a11ea4-9604-0410-9ed3-97b8803252fd
Use guile/python executable as found during configure for tests and some support scripts

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23392 57a11ea4-9604-0410-9ed3-97b8803252fd
Make python test find its test files for out of tree builds

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23393 57a11ea4-9604-0410-9ed3-97b8803252fd
Bug 709589 - make check fails with guile 2

The use of (macro? ) has changed in guile2.
In addition the test script has been reformatted
to make it more readable and easier to detect
where exactly it fails.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23394 57a11ea4-9604-0410-9ed3-97b8803252fd