[DebugInfo] Fix debug information label tests.

[mstojanovic]

Summary

Removed the space in the asm check so that the expression is more general and can also capture MIPS labels which can be surrounded by braces, e.g.:

.4byte        ($tmp1)                 # DW_AT_low_pc

Also changed optimization level to O0 because the DW_TAG_label don't appear on MIPS when -O2 is used.

test/DebugInfo/Generic/debug-label-inline.ll

-; RUN: llc -O2 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc -O0 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
 ;
 ; CHECK: .debug_info contents:
 ; CHECK: [[LABEL_ORIGIN:0x[0-9a-zA-Z]+]]:{{ *}}DW_TAG_label
 ; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"top"
 ; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label-inline.c
 ; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}8
 ; CHECK: DW_TAG_label
 ; CHECK-NEXT: DW_AT_abstract_origin [DW_FORM_ref4] {{.*}}{[[LABEL_ORIGIN]]} "top"

test/DebugInfo/Generic/debug-label.ll

 ;
 ; ASM: [[TOP_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:top
 ; ASM: [[DONE_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:done
 ; ASM-LABEL: debug_info
 ; ASM: DW_TAG_label
 ; ASM-NEXT: DW_AT_name
 ; ASM-NEXT: 1 {{.*}} DW_AT_decl_file
 ; ASM-NEXT: 4 {{.*}} DW_AT_decl_line
-; ASM-NEXT: [[TOP_LOW_PC]] {{.*}} DW_AT_low_pc
+; ASM-NEXT: [[TOP_LOW_PC]]{{.*}} DW_AT_low_pc
 ; ASM: DW_TAG_label
 ; ASM-NEXT: DW_AT_name
 ; ASM-NEXT: 1 {{.*}} DW_AT_decl_file
 ; ASM-NEXT: 7 {{.*}} DW_AT_decl_line
-; ASM-NEXT: [[DONE_LOW_PC]] {{.*}} DW_AT_low_pc
+; ASM-NEXT: [[DONE_LOW_PC]]{{.*}} DW_AT_low_pc
 
 source_filename = "debug-label.c"
 
 define dso_local i32 @foo(i32 %a, i32 %b) !dbg !6 {
 entry:
   %a.addr = alloca i32, align 4
   %b.addr = alloca i32, align 4
   %sum = alloca i32, align 4