Fix a case of `-Wmisleading-indentation` when building with Clang (#43472)
```
In file included from /usr/home/alex/julia/src/codegen.cpp:2005:
In file included from ./intrinsics.cpp:7:
In file included from ./ccall.cpp:322:
./abi_x86.cpp:78:9: warning: misleading indentation; statement is not part of the previous 'if' [-Wmisleading-indentation]
ab.addByValAttr(Ty);
^
./abi_x86.cpp:73:5: note: previous statement is here
if (is_complex64(dt) || is_complex128(dt) || (jl_is_primitivetype(dt) && size <= 8))
^
1 warning generated.
```