[PATCH 3/3] clang-tidy: Don't insist on #ifdef over #if defined()

[David Gibson <david@gibson.dropbear.id.au>]

Commit 036fb8770 ("checksum: add VSX fast path for POWER8/POWER9") changed
an #ifdef to #if defined, in order to match a newly introduced #if which
needs to check two different symbols.  This causes clang-tidy to complain
that the directive could be written more concisely.

In this case consistency with the other #if branch seems more important,
and in general insisting on #ifdef over #if seems unhelpfully pedantic.
Suppress that warning globally.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 .clang-tidy | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/.clang-tidy b/.clang-tidy
index 9d346ec2..773121f5 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -81,6 +81,11 @@ Checks:
     #	precedence over addition in modern mathematical notation. Adding
     #	parentheses to reinforce that certainly won't improve readability.
     - "-readability-math-missing-parentheses"
+
+    # #if defined(FOO) is fine, and can be more consistent with other
+    # #if directives.  Don't insist on #ifdef instead.
+    - "-readability-use-concise-preprocessor-directives"
+
 WarningsAsErrors: "*"
 HeaderFileExtensions:
     - h
-- 
2.53.0