File ignore-Wstring-conversion.patch of Package rust.openSUSE_Leap_15.1_Update

*** rustc-1.30.0-src/src/librustc_llvm/build.rs	2018-10-25 09:00:01.000000000 +1300
--- rust-patch/src/librustc_llvm/build.rs	2018-11-05 07:31:35.672765505 +1300
***************
*** 147,152 ****
--- 147,158 ----
              continue;
          }
  
+         // hack to avoid flag on openSUSE which is incompatible with GCC
+         if flag.starts_with("-W") && flag.contains("string-conversion") {
+             continue;
+         }
+ 
+ 
          cfg.flag(flag);
      }