configure: Simplify OMX check

configure

@@ -2190,6 +2190,7 @@ nvenc_deps_any="dlopen LoadLibrary"
 nvenc_extralibs='$ldl'
 omx_deps="dlopen pthreads"
 omx_extralibs='$ldl'
+omx_rpi_select="omx"
 qsvdec_select="qsv"
 qsvenc_select="qsv"
 vaapi_encode_deps="vaapi"
@@ -4688,12 +4689,10 @@ enabled mmal              && { check_lib interface/mmal/mmal.h mmal_port_connect
                                  check_lib interface/mmal/mmal.h mmal_port_connect -lmmal_core -lmmal_util -lmmal_vc_client -lbcm_host; } ||
                                die "ERROR: mmal not found" &&
                                check_func_headers interface/mmal/mmal.h "MMAL_PARAMETER_VIDEO_MAX_NUM_CALLBACKS"; }
-enabled omx_rpi && enable omx
-enabled omx               && { check_header OMX_Core.h ||
-                                { ! enabled cross_compile && enabled omx_rpi && {
-                                    add_cflags -isystem/opt/vc/include/IL ; }
-                                check_header OMX_Core.h ; } ||
+enabled omx_rpi           && { check_header OMX_Core.h ||
+                               { ! enabled cross_compile && add_cflags -isystem/opt/vc/include/IL && check_header OMX_Core.h ; } ||
                                die "ERROR: OpenMAX IL headers not found"; }
+enabled omx               && { check_header OMX_Core.h || die "ERROR: OpenMAX IL headers not found"; }
 enabled openssl           && { { check_pkg_config openssl openssl/ssl.h OPENSSL_init_ssl ||
                                  check_pkg_config openssl openssl/ssl.h SSL_library_init; } && {
                                add_cflags $openssl_cflags && add_extralibs $openssl_libs; }||