Update ignored tests for dynamic musl

Now that musl supports dynamic libraries (although not by default)
enable the tests that now pass. Additional currently-ignored tests
will pass if rustc is built with crt_static=false in config.toml.

src/test/run-pass-fulldeps/issue-13560.rs

@@ -11,7 +11,6 @@
 // aux-build:issue-13560-1.rs
 // aux-build:issue-13560-2.rs
 // aux-build:issue-13560-3.rs
-// ignore-musl
 
 // Regression test for issue #13560, the test itself is all in the dependent
 // libraries. The fail which previously failed to compile is the one numbered 3.

src/test/run-pass-fulldeps/linkage-visibility.rs

@@ -11,7 +11,6 @@
 // aux-build:linkage-visibility.rs
 // ignore-android: FIXME(#10356)
 // ignore-windows: std::dynamic_lib does not work on Windows well
-// ignore-musl
 // ignore-emscripten no dynamic linking
 
 extern crate linkage_visibility as foo;