- Fixed cut-and-paste error.
- See http://savannah.gnu.org/patch/?7576 for further details.
- Use 'ls -r' rather than non-portable tool 'tac'.
- Simplify filepattern in ls expression so dylib (on OSX) are also detected.
If BDB_CPPFLAGS returns only "-I", the next argument sent to the preprocessor
is treated as a path. There are 2 fixes here:
1. Check in CPPFLAGS, as a user might have manually passed a path to check.
2. Ensure the value is not empty before setting BDB_CPPFLAGS to "-I value"