Fixed bug 4154 - Fix three empty variable tests in configure Zack Middleton Running top-level SDL configure on macOS 10.11 resulted in the errors below because automake removed the brackets about the tests. ./configure: line 15756: : command not found ./configure: line 15759: -Iinclude -I/Users/zack/SDL/include -idirafter /Users/zack/SDL/src/video/khronos : No such file or directory ./configure: line 15763: : command not found