format: add rule for single-line conditions

Trying to uniformize the project coding style to keep consistency.

Signed-off-by: Nathan Gauër <brioche@google.com>

.clang-format

diff --git a/.clang-format b/.clang-format
index 5bf32ea..a9b027b 100644
--- a/.clang-format
+++ b/.clang-format
@@ -1,7 +1,8 @@
 ---
-Language: Cpp
+AllowShortIfStatementsOnASingleLine: false
 BasedOnStyle: Google
 DerivePointerAlignment: false
+Language: Cpp
 SortIncludes: true
 AllowShortIfStatementsOnASingleLine: true
 ...