package/ola: stageprofi and usbdmx needs gcc >= 4.9

Fix the following build failure raised since re-introduction of the
package in commit 16ff948444c3978d63f483344a3d92d994c64312:

configure: error: compiler with C11 support is required to build libusb

Fixes:
 - http://autobuild.buildroot.org/results/7b15e23392805f5109c136a5aa870ddf49f48814

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/ola/Config.in

@@ -153,10 +153,14 @@ config BR2_PACKAGE_OLA_PLUGIN_SPI
 
 config BR2_PACKAGE_OLA_PLUGIN_STAGEPROFI
 	bool "stageprofi"
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # libusb
 	select BR2_PACKAGE_LIBUSB
 	help
 	  Build StageProfi plugin for OLA.
 
+comment "stageprofi needs a toolchain w/ gcc >= 4.9"
+	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
+
 config BR2_PACKAGE_OLA_PLUGIN_UARTDMX
 	bool "uartdmx"
 	help
@@ -164,10 +168,14 @@ config BR2_PACKAGE_OLA_PLUGIN_UARTDMX
 
 config BR2_PACKAGE_OLA_PLUGIN_USBDMX
 	bool "usbdmx"
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # libusb
 	select BR2_PACKAGE_LIBUSB
 	help
 	  Build USB DMX plugin for OLA.
 
+comment "usbdmx needs a toolchain w/ gcc >= 4.9"
+	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
+
 config BR2_PACKAGE_OLA_PLUGIN_USBPRO
 	bool "usbpro"
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # libusb