[PATCH v2 2/2] Makefile: add style build rule

Add the 'style' build rule which will run git-clang-format on the diff
between HEAD and the current worktree.  The result is a diff of
suggested changes.

Signed-off-by: Brandon Williams <redacted>
---
 Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Makefile b/Makefile
index ba4359ef8..acfd096b7 100644
--- a/Makefile
+++ b/Makefile

@@ -2414,6 +2414,10 @@ $(SP_OBJ): %.sp: %.c GIT-CFLAGS FORCE
 .PHONY: sparse $(SP_OBJ)
 sparse: $(SP_OBJ)
 
+.PHONY: style
+style:
+	git clang-format --style file --diff --extensions c,h
+
 check: common-cmds.h
 	@if sparse; \
 	then \

-- 
2.14.1.480.gb18f417b89-goog