Make get_cpp_link_stdlib public, and fix two doc warnings

Author: SallySoul

src/lib.rs

@@ -684,7 +684,7 @@ impl Build {
     /// Set the standard library to link against when compiling with C++
     /// support.
     ///
-    /// See [`get_cpp_link_stdlib`](cc::Build::get_cpp_link_stdlib) documentation
+    /// See [`get_cpp_link_stdlib`](Build::get_cpp_link_stdlib) documentation
     /// for the default value.
     /// If the `CXXSTDLIB` environment variable is set, its value will
     /// override the default value, but not the value explicitly set by calling
@@ -2282,11 +2282,11 @@ impl Build {
     }
 
     /// Returns the C++ standard library:
-    /// 1. If [cpp_link_stdlib](cc::Build::cpp_link_stdlib) is set, uses its value.
+    /// 1. If [cpp_link_stdlib](Build::cpp_link_stdlib) is set, uses its value.
     /// 2. Else if the `CXXSTDLIB` environment variable is set, uses its value.
     /// 3. Else the default is `libc++` for OS X and BSDs, `libc++_shared` for Android,
     /// `None` for MSVC and `libstdc++` for anything else.
-    fn get_cpp_link_stdlib(&self) -> Result<Option<String>, Error> {
+    pub fn get_cpp_link_stdlib(&self) -> Result<Option<String>, Error> {
         match self.cpp_link_stdlib.clone() {
             Some(s) => Ok(s),
             None => {