gimp: Remove -Qunused-arguments from complier cmdline with clang

[kraj]

This supresses the -msseX argument diagnostics on non-x86 architectures and meson wrongly decided to enable SSE on these biulds which ends up in

                               │

│| In file included from ../gimp-3.0.2/app/gegl/gimp-gegl-loops-sse2.c:36: │
│| /mnt/b/yoe/master/build/tmp/work/riscv64-yoe-linux/gimp/3.0.2/recipe-sysroot-native/usr/lib/clang/20/include/emmintrin.h:14:2: error: "This header is only meant to be used on x86 and│
│ x64 architecture" │
│| 14 | #error "This header is only meant to be used on x86 and x64 architecture" │
│| | ^ │
│| In file included from ../gimp-3.0.2/app/gegl/gimp-gegl-loops-sse2.c:36:

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