perf script: Add newline after uregs output

This change makes it much easier to easily distinguish between
consecutive samples by keeping the empty line between them, like we see
when we do not enable uregs output.

Before:

  cpp-inlining 28298 [-01] 54837.342780:    3068085 cycles:pp:
              7ffff7c96709 __hypot_finite+0xa9 (/usr/lib/libm-2.28.so)
              ...
   ABI:2    AX:0x0    BX:0x40f56cf6    CX:0x294a3ae7    ...
  cpp-inlining 28298 [-01] 54837.344493:    2881929 cycles:pp:
              7ffff7c96696 __hypot_finite+0x36 (/usr/lib/libm-2.28.so)
              ...
   ABI:2    AX:0x40d440c7    BX:0x40d440c7    CX:0x4d45e5da    ...

After:

  cpp-inlining 28298 [-01] 54837.342780:    3068085 cycles:pp:
              7ffff7c96709 __hypot_finite+0xa9 (/usr/lib/libm-2.28.so)
              ...
   ABI:2    AX:0x0    BX:0x40f56cf6    CX:0x294a3ae7    ...

  cpp-inlining 28298 [-01] 54837.344493:    2881929 cycles:pp:
              7ffff7c96696 __hypot_finite+0x36 (/usr/lib/libm-2.28.so)
              ...
   ABI:2    AX:0x40d440c7    BX:0x40d440c7    CX:0x4d45e5da    ...

Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20181107093705.16346-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>