package/uhd: fix build with ARM without NEON

UHD has two issues with ARM:
1/ NEON_SIMD_ENABLE is always enabled when architecture is ARM. But NEON isn't
   necessarily support in the CPU
2/ when NEON is supported -mfpu=neon must be passed to the compiler (not
   automatically done by UHD)

Fixes:
- http://autobuild.buildroot.net/results/2519bd075b8c021b440677297b32f16b1c3cc3dd/
- http://autobuild.buildroot.net/results/99d9979be4f37c42390c87b1afd4cd33bac07f5e/
- http://autobuild.buildroot.net/results/cabc7a87ee869d6bac7d092c1a4fcfcdac22a96e/

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/uhd/uhd.mk

@@ -38,6 +38,17 @@ UHD_CONF_OPTS = \
 	-DENABLE_UTILS=OFF \
 	-DENABLE_X300=OFF
 
+# As soon as architecture is ARM, uhd will try to use NEON.
+# But not all ARM cores have NEON support.
+# When CPU support NEON -mfpu=neon must be added to CXX_FLAGS
+ifeq ($(BR2_ARM_CPU_HAS_NEON),y)
+UHD_CONF_OPTS += -DCMAKE_CXX_FLAGS="$(TARGET_CXXFLAGS) -mfpu=neon"
+UHD_CONF_OPTS += -DNEON_SIMD_ENABLE=ON
+else
+UHD_CONF_OPTS += -Dhave_mfpu_neon=0
+UHD_CONF_OPTS += -DNEON_SIMD_ENABLE=OFF
+endif
+
 ifeq ($(BR2_PACKAGE_ORC),y)
 UHD_DEPENDENCIES += orc
 endif