toolchain-wrapper.c: unbreak BR_CROSS_PATH_ABS handling

Fixes #8386

We should check if BR_CROSS_PATH_ABS is defined, not if it evalutates to
true for the pre processor.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

toolchain/toolchain-wrapper.c

@@ -144,7 +144,7 @@ int main(int argc, char **argv)
 	/* Fill in the relative paths */
 #ifdef BR_CROSS_PATH_REL
 	ret = snprintf(path, sizeof(path), "%s/" BR_CROSS_PATH_REL "/%s", absbasedir, basename);
-#elif BR_CROSS_PATH_ABS
+#elif defined(BR_CROSS_PATH_ABS)
 	ret = snprintf(path, sizeof(path), BR_CROSS_PATH_ABS "/%s", basename);
 #else /* BR_CROSS_PATH_SUFFIX */
 	ret = snprintf(path, sizeof(path), "%s/usr/bin/%s" BR_CROSS_PATH_SUFFIX, absbasedir, basename);