[ELF] Reorganize "is only supported on" tests and fix some diagnostics

Author: MaskRay

lld/ELF/Driver.cpp

@@ -317,10 +317,10 @@ static void checkOptions() {
     error("--fix-cortex-a8 is only supported on ARM targets");
 
   if (config->tocOptimize && config->emachine != EM_PPC64)
-    error("--toc-optimize is only supported on the PowerPC64 target");
+    error("--toc-optimize is only supported on PowerPC64 targets");
 
   if (config->pcRelOptimize && config->emachine != EM_PPC64)
-    error("--pcrel--optimize is only supported on the PowerPC64 target");
+    error("--pcrel-optimize is only supported on PowerPC64 targets");
 
   if (config->pie && config->shared)
     error("-shared and -pie may not be used together");

lld/test/ELF/aarch64-cortex-a53-843419-cli.s

@@ -0,0 +1,14 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t
+
+# RUN: not ld.lld %t --fix-cortex-a53-843419 -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR-843419
+# ERR-843419: error: --fix-cortex-a53-843419 is only supported on AArch64 targets
+
+# RUN: not ld.lld %t --pcrel-optimize -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR-PCREL
+# ERR-PCREL: error: --pcrel-optimize is only supported on PowerPC64 targets
+
+# RUN: not ld.lld %t --toc-optimize -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR-TOC
+# ERR-TOC: error: --toc-optimize is only supported on PowerPC64 targets
+
+.globl _start
+_start: