Removed unnecessary output of linker options when linker is not installed

It's unnecessary to print the linker options if there is no linker installed.
Currently, for libraries, the output is still printed, see #46998 for
discussion

Author: fschutt

src/librustc_trans/back/link.rs

@@ -708,10 +708,25 @@ fn link_natively(sess: &Session,
             info!("linker stdout:\n{}", escape_string(&prog.stdout));
         },
         Err(e) => {
-            sess.struct_err(&format!("could not exec the linker `{}`: {}", pname.display(), e))
-                .note(&format!("{:?}", &cmd))
-                .emit();
-            if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
+            let linker_not_found = e.kind() == io::ErrorKind::NotFound;
+
+            let mut linker_error = {
+                if linker_not_found {
+                    sess.struct_err(&format!("linker `{}` not found", pname.display()))
+                } else {
+                    sess.struct_err(&format!("could not exec the linker `{}`", pname.display()))
+                }
+            };
+
+            linker_error.note(&format!("{}", e));
+
+            if !linker_not_found {
+                linker_error.note(&format!("{:?}", &cmd));
+            }
+
+            linker_error.emit();
+
+            if sess.target.target.options.is_like_msvc && linker_not_found {
                 sess.note_without_error("the msvc targets depend on the msvc linker \
                     but `link.exe` was not found");
                 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \

src/test/compile-fail/issue-10755.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // compile-flags: -C linker=llllll -Z linker-flavor=ld
-// error-pattern: the linker `llllll`
+// error-pattern: linker `llllll` not found
 
 fn main() {
 }