Normalize T14999 test output some more

@osa1 reported that the output on his machine has extra newlines:
https://phabricator.haskell.org/D4606#129092. This collapses consecutive
newlines.

testsuite/tests/codeGen/should_compile/Makefile

@@ -36,5 +36,5 @@ debug:
 
 T14999:
 	'$(TEST_HC)' $(TEST_HC_OPTS) -O2 -g -c T14999.cmm -o T14999.o
-	gdb --batch -ex 'file T14999.o' -ex 'disassemble stg_catch_frame_info' --nx | tr -s '[:blank:]'
-	readelf --debug-dump=frames-interp T14999.o | tr -s '[:blank:]'
+	gdb --batch -ex 'file T14999.o' -ex 'disassemble stg_catch_frame_info' --nx | tr -s '[[:blank:]\n]'
+	readelf --debug-dump=frames-interp T14999.o | tr -s '[[:blank:]\n]'

testsuite/tests/codeGen/should_compile/T14999.stdout

@@ -3,14 +3,11 @@ Dump of assembler code for function stg_catch_frame_info:
  0x0000000000000014 <+4>:	jmpq *0x0(%rbp)
 End of assembler dump.
 Contents of the .debug_frame section:
-
 00000000 0000000000000014 ffffffff CIE "" cf=1 df=-8 ra=16
  LOC CFA rbp rsp ra 
 0000000000000000 rbp+0 v+0 s c+0 
-
 00000018 000000000000002c 00000000 FDE cie=00000000 pc=000000000000000f..0000000000000017
  LOC CFA rbp rsp ra 
 000000000000000f rbp+0 v+0 s c+0 
 000000000000000f rbp+24 v+0 s c+0 
 0000000000000014 rbp+0 v+0 s c+0 
-