toolchain: enable libquadmath for PowerPC with VSX

float128 is available on PowerPC with VSX [1] but it requires
libquadmath support.

[1] https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Floating-Types.html

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Cyril Bur <cyrilbur@gmail.com>
Cc: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

toolchain/Config.in

@@ -833,9 +833,11 @@ config BR2_TOOLCHAIN_HAS_ATOMIC
 # - At least, libquadmath is available on:
 #   - i*86
 #   - x86_64
+#   - PowerPC with vector scalar (VSX) instruction set
 # - When available, libquadmath requires wchar support.
 config BR2_TOOLCHAIN_HAS_LIBQUADMATH
 	bool
 	default y if BR2_i386 || BR2_x86_64
+	default y if BR2_POWERPC_CPU_HAS_VSX
 
 endmenu