Remove execinfo.h from test_redox

Author: JohnTitor

libc-test/build.rs

@@ -537,7 +537,6 @@ fn test_redox(target: &str) {
         "dirent.h",
         "dlfcn.h",
         "errno.h",
-        "execinfo.h",
         "fcntl.h",
         "glob.h",
         "grp.h",