gdb: drop duplicate dependencies

Commit 1e3738db42919cb4487f7a64381ac7d3090d0e1f ("package/gdb: rework
dependency for C++11") erroneously added duplicate dependencies in
package/gdb/Config.in related to gcc 4.8 and C++ dependency.

One copy of those dependencies was below the select causing a
check-package warning.

Fixes:

package/gdb/Config.in:28: attributes order: type, default, depends on, select, help (http://nightly.buildroot.org/#_config_files)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gdb/Config.in

@@ -25,8 +25,6 @@ config BR2_PACKAGE_GDB
 	# one from the external toolchain should be used.
 	select BR2_PACKAGE_GDB_SERVER if \
 		(!BR2_PACKAGE_GDB_DEBUGGER && !BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY)
-	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_PACKAGE_GDB_NEEDS_CXX11
-	depends on BR2_INSTALL_LIBSTDCPP || !BR2_PACKAGE_GDB_NEEDS_CXX11
 	help
 	  GDB, the GNU Project debugger, allows you to see what is
 	  going on `inside' another program while it executes -- or