[NFC][ELF][CHERI] Make CaptablePermissions a bit less ugly

Note that the clang-format directives are in anticipation of future
additions, where we will still want to keep the equals signs, and thus
bit numbers, aligned to make it easier to read.

Author: jrtc27

lld/ELF/Arch/Cheri.cpp

@@ -314,12 +314,15 @@ static uint64_t getTargetSize(Ctx &ctx, const CheriCapRelocLocation &location,
 
 template <class ELFT>
 struct CaptablePermissions {
-  static const uint64_t function = UINT64_C(1)
-                                   << ((sizeof(typename ELFT::uint) * 8) - 1);
-  static const uint64_t readOnly = UINT64_C(1)
-                                   << ((sizeof(typename ELFT::uint) * 8) - 2);
-  static const uint64_t indirect = UINT64_C(1)
-                                   << ((sizeof(typename ELFT::uint) * 8) - 3);
+  static constexpr uint64_t permissionBit(uint64_t bit) {
+    return UINT64_C(1) << ((sizeof(typename ELFT::uint) * 8) - bit);
+  }
+
+  // clang-format off
+  static const uint64_t function = permissionBit(1);
+  static const uint64_t readOnly = permissionBit(2);
+  static const uint64_t indirect = permissionBit(3);
+  // clang-format on
 };
 
 template <class ELFT>