webkitgtk: Use gcc to compile for arm target

Builds with clang run into compiler errors

<inline asm>:320:1: error: Relocation Not In Range
  320 | movw r4, #:lower16:.Lllint_op_tail_call_varargs - .Lllint_relativePCBase
      | ^

(From OE-Core rev: be459bf17d5e47c51d96da1a571de01790c277b9)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-sato/webkit/webkitgtk_2.48.1.bb

@@ -176,3 +176,5 @@ src_package_preprocess () {
             ${B}/WebKitGTK/DerivedSources/webkit/*.cpp
 }
 
+# Clang-20 issue - https://github.com/llvm/llvm-project/issues/132322
+TOOLCHAIN:arm = "gcc"