[llvm-objdump] Print newlines before and after "Disassembly of section ...:"

This improves readability and the behavior is consistent with GNU objdump.

The new test test/tools/llvm-objdump/X86/disassemble-section-name.s
checks we print newlines before and after "Disassembly of section ...:"

Differential Revision: https://reviews.llvm.org/D61127

llvm-svn: 359668
diff --git a/lld/test/ELF/relocation-b-aarch64.test b/lld/test/ELF/relocation-b-aarch64.test
index ff4a82f..15ad4a6 100644
--- a/lld/test/ELF/relocation-b-aarch64.test
+++ b/lld/test/ELF/relocation-b-aarch64.test
@@ -8,6 +8,7 @@
 # immediate. We use this property to overwrite instructions with a branch.
 
 # CHECK: Disassembly of section .text:
+# CHECK-EMPTY:
 # CHECK-NEXT: foo:
 # CHECK-NEXT:    210000:        01 00 00 14     b       #4
 # CHECK: bar: