cygpath only exists in Windows build, 2nd try
cygpath only exists in Windows build, 2nd try

Avoid the $(shell cygpath) calls when not on windows. The error message
is harmless, but it bothers me. I think gb_ExternalProject_use_autoconf
(and the AUTOCONF_WRAPPERS definition) should be moved to
gbuild/platform.

Change-Id: Ia537c5dac682f93ce5efe5c54b97b3a257cb6136

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core