support/config-fragments: add RISC-V 64-bit musl autobuild config

Add a RISC-V 64-bit autobuild configuration for the internal
toolchain with musl.

Signed-off-by: Mark Corbin <mark.corbin@embecosm.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/config-fragments/autobuild/br-riscv64-musl.config

@@ -0,0 +1,3 @@
+BR2_riscv=y
+BR2_TOOLCHAIN_BUILDROOT_MUSL=y
+BR2_TOOLCHAIN_BUILDROOT_CXX=y

support/config-fragments/autobuild/toolchain-configs.csv

@@ -53,6 +53,7 @@ support/config-fragments/autobuild/br-powerpc-e500mc-full.config,x86_64
 support/config-fragments/autobuild/br-powerpc-internal-full.config,any
 support/config-fragments/autobuild/br-riscv32.config,x86_64
 support/config-fragments/autobuild/br-riscv64.config,x86_64
+support/config-fragments/autobuild/br-riscv64-musl.config,any
 support/config-fragments/autobuild/br-sh4-full.config,x86_64
 support/config-fragments/autobuild/br-sparc-uclibc.config,x86_64
 support/config-fragments/autobuild/br-sparc64-glibc.config,x86_64