compiler: change canonical path for backend ABI source files

CMakeLists.txt

@@ -549,34 +549,6 @@ set(ZIG_STAGE2_SOURCES
     src/Value.zig
     src/Zcu.zig
     src/Zcu/PerThread.zig
-    src/arch/riscv64/abi.zig
-    src/arch/riscv64/bits.zig
-    src/arch/riscv64/CodeGen.zig
-    src/arch/riscv64/Emit.zig
-    src/arch/riscv64/encoding.zig
-    src/arch/riscv64/Lower.zig
-    src/arch/riscv64/Mir.zig
-    src/arch/riscv64/mnem.zig
-    src/arch/sparc64/CodeGen.zig
-    src/arch/sparc64/Emit.zig
-    src/arch/sparc64/Mir.zig
-    src/arch/sparc64/abi.zig
-    src/arch/sparc64/bits.zig
-    src/arch/wasm/CodeGen.zig
-    src/arch/wasm/Emit.zig
-    src/arch/wasm/Mir.zig
-    src/arch/wasm/abi.zig
-    src/arch/x86/bits.zig
-    src/arch/x86_64/CodeGen.zig
-    src/arch/x86_64/Disassembler.zig
-    src/arch/x86_64/Emit.zig
-    src/arch/x86_64/Encoding.zig
-    src/arch/x86_64/Lower.zig
-    src/arch/x86_64/Mir.zig
-    src/arch/x86_64/abi.zig
-    src/arch/x86_64/bits.zig
-    src/arch/x86_64/encoder.zig
-    src/arch/x86_64/encodings.zon
     src/clang.zig
     src/clang_options.zig
     src/clang_options_data.zig