[PATCH 6.12.y] rust: allow `clippy::collapsible_if` globally

[Miguel Ojeda <ojeda@kernel.org>]

Similar to `clippy::collapsible_match` (globally allowed in the previous
commit), the `clippy::collapsible_if` lint [1] can make code harder to
read in certain cases.

Thus just let developers decide on their own.

Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Suggested-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/rust-for-linux/DGROP5CHU1QZ.1OKJRAUZXE9WC@garyguo.net/
Link: https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if [1]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260426144201.227108-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
(cherry picked from commit 2adc8664018c1cc595c7c0c98474a33c7fe32a85)
[ Removed Binder change. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
Greg/Sasha: I based this on the other one, i.e. this needs to be applied
after the one I am replying to.

 Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Makefile b/Makefile
index 2c6b5339c471..fe352fdd6d7c 100644
--- a/Makefile
+++ b/Makefile
@@ -453,6 +453,7 @@ export rust_common_flags := --edition=2021 \
 			    -Wrust_2018_idioms \
 			    -Wunreachable_pub \
 			    -Wclippy::all \
+			    -Aclippy::collapsible_if \
 			    -Aclippy::collapsible_match \
 			    -Wclippy::ignored_unit_patterns \
 			    -Wclippy::mut_mut \
--
2.54.0