Merge pull request #11209 from NilsLankila/patch-1

fix issue 20824 - error messages generated by dmd build script can be…
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

src/build.d

@@ -1806,7 +1806,7 @@ Returns: nothing but enables `throw abortBuild` to convey the resulting behavior
 */
 BuildException abortBuild(string msg = "Build failed!")
 {
-    throw new BuildException("ERROR: " ~ msg);
+    throw new BuildException(msg);
 }
 
 class BuildException : Exception