[PATCH 4/4] meson: add rule to run 'git clang-format'

The Makefile has a 'style' rule to run 'git clang-format'. While Meson
intrinsically supports a 'clang-format' target, which can be run when
using the ninja backend by running 'ninja clang-format', this runs the
formatting on all existing files.

Our Meson build doesn't yet support a way to run 'git clang-format',
which runs the formatter between the working directory and commit
provided. Add a new 'style' target to Meson to mimic the target in the
Makefile.

Signed-off-by: Karthik Nayak <redacted>
---
 meson.build | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/meson.build b/meson.build
index 7fea4a34d6..578db26df2 100644
--- a/meson.build
+++ b/meson.build

@@ -2144,6 +2144,18 @@ if headers_to_check.length() != 0 and compiler.get_argument_syntax() == 'gcc'
   alias_target('check-headers', hdr_check)
 endif
 
+clang_format = find_program('clang-format', required: false)
+if clang_format.found()
+  run_target('style',
+    command: [
+      'git', 'clang-format',
+      '--style', 'file',
+      '--diff',
+      '--extensions', 'c,h'
+    ]
+  )
+endif
+
 foreach key, value : {
   'DIFF': diff.full_path(),
   'GIT_SOURCE_DIR': meson.project_source_root(),

-- 
2.49.0