package/gdb: prevent gdbserver being selected for RISC-V builds

There is currently no version of gdbserver for RISC-V. Until this
is implemented we will prevent both the direct and indirect
selection of gdbserver for RISC-V builds. In practice this means
that 'cross gdb for the host' cannot be selected and that
'full debugger' must be automatically selected for the gdb target
package.

[Peter: simplify logic, add comment]
Signed-off-by: Mark Corbin <mark.corbin@embecosm.com>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gdb/Config.in

@@ -20,6 +20,8 @@ config BR2_PACKAGE_GDB
 	depends on BR2_PACKAGE_GDB_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_PACKAGE_GDB_NEEDS_CXX11
 	depends on BR2_INSTALL_LIBSTDCPP || !BR2_PACKAGE_GDB_NEEDS_CXX11
+	# no gdbserver on riscv
+	select BR2_PACKAGE_GDB_DEBUGGER if BR2_riscv
 	# When the external toolchain gdbserver is copied to the
 	# target, we don't allow building a separate gdbserver. The
 	# one from the external toolchain should be used.
@@ -46,6 +48,7 @@ if BR2_PACKAGE_GDB
 config BR2_PACKAGE_GDB_SERVER
 	bool "gdbserver"
 	depends on !BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY
+	depends on !BR2_riscv
 	help
 	  Build the gdbserver stub to run on the target.
 	  A full gdb is needed to debug the progam.

package/gdb/Config.in.host

@@ -7,6 +7,7 @@ config BR2_PACKAGE_HOST_GDB_ARCH_SUPPORTS
 	depends on !BR2_microblaze
 	depends on !BR2_nios2
 	depends on !BR2_or1k
+	depends on !BR2_riscv
 
 comment "Host GDB Options"
 	depends on !BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY