compiler: Remove warning about superfluous compiler-rt libraries.

* This warning's wording is actually inaccurate when using the -fno-compiler-rt
  or -rtlib=none options.
* It's not all that helpful; it's already understood that these libraries are
  part of the compiler, so printing a warning is just noise. In practice, this
  warning would always happen when building upstream musl, for example.
* We don't warn when we satisfy -lunwind using our bundled libunwind either, or
  various libc libraries using our bundled libc, or when providing libc++, etc.
  So I really don't think we should be warning here either.

src/main.zig

@@ -3838,10 +3838,7 @@ fn createModule(
                         create_module.opts.link_libunwind = true;
                         continue;
                     },
-                    .only_compiler_rt => {
-                        warn("ignoring superfluous library '{s}': this dependency is fulfilled instead by compiler-rt which zig unconditionally provides", .{lib_name});
-                        continue;
-                    },
+                    .only_compiler_rt => continue,
                 }
 
                 if (target.isMinGW()) {