fix(gen): empty SIMD baseline emits valid '{ "-w" }' not '{ , "-w" }'

On aarch64/macOS baseline_m is empty; the old f-string left a leading comma.
Join '-w' inside the list so both empty (macOS) and non-empty (linux x86) are valid lua.

Author: Sunrisepeak

tools/compat-opencv/gen_descriptor.py

@@ -455,8 +455,8 @@ def defines_lua(defset):
 {deps_line}        include_dirs = {{
             {lua_list(incdirs, " " * 12)}
         }},
-        cxxflags = {{ {", ".join(f'"{m}"' for m in baseline_m)}, "-w" }},
-        cflags   = {{ {", ".join(f'"{m}"' for m in baseline_m)}, "-w" }},
+        cxxflags = {{ {", ".join([f'"{m}"' for m in baseline_m] + ['"-w"'])} }},
+        cflags   = {{ {", ".join([f'"{m}"' for m in baseline_m] + ['"-w"'])} }},
         flags = {{
             {("\n" + " " * 12).join(flags_entries)}
         }},