gnupg: Read GNUPG_BINDIR from environment variables for nativesdk

gnupg: Read GNUPG_BINDIR from environment variables for nativesdk

There is already a relocate.patch for native which is used for reading
GNUPG_BINDIR from environment variables, now also enable it for nativesdk.
Otherwise, command like the following one doesn't work for nativesdk:

$ gpg-connect-agent --homedir ../keys/ reloadagent /bye
gpg-connect-agent: no running gpg-agent - starting '/opt/path/to/sysroots/x86_64-wrlinuxsdk-linux/usr/bin/gpg-agent'
gpg-connect-agent: failed to start agent '/opt/path/sysroots/x86_64-wrlinuxsdk-linux/usr/bin/gpg-agent': No such file or directory

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>