configure.ac: don't use == with test

Although it works, it's not the correct thing to do.

v2: Rebase
v3: Rebase

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Tobias Droste <tdroste@gmx.de> (v1)
diff --git a/configure.ac b/configure.ac
index c292532..9f94d8b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2378,14 +2378,14 @@
     done
 fi
 
-if test "x$enable_gallium_llvm" == "xyes" -a "$with_gallium_drivers"; then
+if test "x$enable_gallium_llvm" = "xyes" -a "$with_gallium_drivers"; then
     llvm_require_version $LLVM_REQUIRED_GALLIUM "gallium"
     llvm_add_default_components "gallium"
 fi
 
 dnl We need to validate some needed dependencies for renderonly drivers.
 
-if test "x$HAVE_GALLIUM_ETNAVIV" != xyes -a "x$HAVE_GALLIUM_IMX" == xyes  ; then
+if test "x$HAVE_GALLIUM_ETNAVIV" != xyes -a "x$HAVE_GALLIUM_IMX" = xyes  ; then
     AC_ERROR([Building with imx requires etnaviv])
 fi