https://bugs.gentoo.org/723314
--- a/configure.ac
+++ b/configure.ac
@@ -208,7 +208,7 @@
 AC_ARG_VAR([CC_FOR_BUILD], [C compiler for programs to be run on the build system])
 AC_ARG_VAR([CFLAGS_FOR_BUILD], [C compiler flags for CC_FOR_BUILD])
 AC_MSG_CHECKING([for the host compiler])
-if test "x$build" == "x$host" ; then
+if test "x$build" = "x$host" ; then
   # Not cross-compiling.
   CC_FOR_BUILD=$CC
   CFLAGS_FOR_BUILD=$CFLAGS