libc-test: remove workarounds for musl <1.2.3

This commit removes various workarounds for now unsupported versions of
musl libc, such as missing functions.

Author: xbjfk

libc-test/build.rs

@@ -4218,12 +4218,6 @@ fn test_linux(target: &str) {
             if loongarch64 && (name == "MFD_NOEXEC_SEAL" || name == "MFD_EXEC") {
                 return true;
             }
-            // FIXME(musl): Requires musl >= 1.2
-            if name == "SO_PREFER_BUSY_POLL"
-                || name == "SO_BUSY_POLL_BUDGET"
-            {
-                return true;
-            }
             // FIXME(musl): Not in musl yet
             if name == "SO_NETNS_COOKIE"
                 || name == "SO_BUF_LOCK"
@@ -4640,20 +4634,12 @@ fn test_linux(target: &str) {
             // assume it's a int instead.
             "getnameinfo" if uclibc => true,
 
-            // FIXME(musl): This needs musl 1.2.2 or later.
-            "gettid" if musl => true,
-
             // Needs glibc 2.33 or later.
             "mallinfo2" => true,
 
-            "reallocarray" if musl => true,
-
             // Not defined in uclibc as of 1.0.34
             "gettid" if uclibc => true,
 
-            // Needs musl 1.2.3 or later.
-            "pthread_getname_np" if musl => true,
-
             // pthread_sigqueue uses sigval, which was initially declared
             // as a struct but should be defined as a union. However due
             // to the issues described here: https://github.com/rust-lang/libc/issues/2816