enabled building gen_test_char for running on build when cross-compiling;

this does not change code for any platform unless CROSS_COMPILE is defined.
Backport of r795971 - reviewed by trawick, rjung.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@1002901 13f79535-47bb-0310-9956-ffa450edef68