MSVC: remove =static from Cargo link command

rust-lang/rust#72785 introduced a breaking
change for MSVC targets that causes linking against a static library to
fail when using `cargo:rustc-link-lib=static`. As a workaround, remove
`=static` from the MSVC code until Rust allows disabling whole archive
linking.

src/msvc.rs

@@ -96,7 +96,7 @@ impl Build {
                         "cargo:rustc-link-search=native=",
                         out_file.parent().expect("empty parent").to_string_lossy(),
                         "\n",
-                        "cargo:rustc-link-lib=static=",
+                        "cargo:rustc-link-lib=",
                         out_file
                             .file_stem()
                             .expect("empty filename")