kcargo.sh: set target platform to Shodan

Set --features CONFIG_PLAT_SHODAN for crates that require a target
platform to compile. Ideally this would track env(PLATFORM) but that's
more complicated and will be done separately.

Change-Id: I6f20e959c6a9d763807c17ae5a05a87cfd599efb

kcargo.sh

diff --git a/kcargo.sh b/kcargo.sh
index afaddc3..1de8fd4 100755
--- a/kcargo.sh
+++ b/kcargo.sh
@@ -32,6 +32,7 @@
 
 CARGO="${CARGO_HOME}/bin/cargo +${CANTRIP_RUST_VERSION}"
 CARGO_TARGET="--target riscv32imac-unknown-none-elf"
+CARGO_TARGET="--target ${RUST_TARGET:-riscv32imac-unknown-none-elf} --features CONFIG_PLAT_SHODAN"
 CARGO_OPTS='-Z unstable-options -Z avoid-dev-deps'
 
 export RUSTFLAGS='-Z tls-model=local-exec'