Makefile: add UNSAFE_BLOCKS parameter

`make clippy UNSAFE_BLOCKS=1` will enable
`clippy::undocumented_unsafe_blocks` warnings. This can help the effort
to reduce them. If it's set we remove `-D warnings` since `clippy`
will exit after checking the first module that contains them.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

Author: stefano-garzarella

Makefile

@@ -9,6 +9,11 @@ ifneq ($(FEATURES_TEST),)
 SVSM_ARGS_TEST += --features ${FEATURES_TEST}
 endif
 
+CLIPPY_ARGS ?= -D warnings
+ifdef UNSAFE_BLOCKS
+CLIPPY_ARGS = -W clippy::undocumented_unsafe_blocks
+endif
+
 ifdef RELEASE
 TARGET_PATH=release
 CARGO_ARGS += --release
@@ -184,11 +189,11 @@ bin/svsm-test.bin: bin/svsm-test
 	objcopy -O binary $< $@
 
 clippy:
-	cargo clippy --all-features --workspace --exclude svsm --exclude stage1 --exclude svsm-fuzz -- -D warnings
-	RUSTFLAGS="--cfg fuzzing" cargo clippy --all-features --package svsm-fuzz -- -D warnings
-	cargo clippy --all-features --package svsm --target x86_64-unknown-none -- -D warnings
-	cargo clippy --all-features --package stage1 --target x86_64-unknown-none -- -D warnings ${STAGE1_RUSTC_ARGS}
-	cargo clippy --all-features --workspace --tests --exclude packit -- -D warnings
+	cargo clippy --all-features --workspace --exclude svsm --exclude stage1 --exclude svsm-fuzz -- ${CLIPPY_ARGS}
+	RUSTFLAGS="--cfg fuzzing" cargo clippy --all-features --package svsm-fuzz -- ${CLIPPY_ARGS}
+	cargo clippy --all-features --package svsm --target x86_64-unknown-none -- ${CLIPPY_ARGS}
+	cargo clippy --all-features --package stage1 --target x86_64-unknown-none -- ${CLIPPY_ARGS} ${STAGE1_RUSTC_ARGS}
+	cargo clippy --all-features --workspace --tests --exclude packit -- ${CLIPPY_ARGS}
 
 clean:
 	cargo clean