[test] Improve symbol-location.s to check --defsym

Author: MaskRay

lld/test/ELF/linkerscript/symbol-location.s

@@ -2,13 +2,18 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
 # RUN: echo 'foo = _start;' > %t.script
 # RUN: not ld.lld -shared -T %t.script %t.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld -shared --defsym 'foo = _start' %t.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=CHECK2
 
 ## Here we check that symbol 'foo' location is reported properly.
 
 # CHECK: error: relocation R_X86_64_PC32 cannot be used against symbol 'foo'
 # CHECK: >>> defined in {{.*}}.script:1
 # CHECK: >>> referenced by {{.*}}.o:(.text+0x1)
 
+# CHECK2: error: relocation R_X86_64_PC32 cannot be used against symbol 'foo'
+# CHECK2: >>> defined in --defsym{{$}}
+# CHECK2: >>> referenced by {{.*}}.o:(.text+0x1)
+
 .text
 .globl _start
 _start: