parsAndCutElf: convert line to str

Without this change, building with python3.x (python3.5 tested) as
/usr/bin/python will result in the following error:

Traceback (most recent call last):
  File "./parsAndCutElf.py", line 79, in <module>
    parserElf(sys.argv)
  File "./parsAndCutElf.py", line 54, in parserElf
    if( (line.find(firstSection) != -1) ):
TypeError: a bytes-like object is required, not 'str'

Change-Id: I0220d0457371349d0a77ac042484fd03f8a984da
Signed-off-by: Marty E. Plummer <hanetzer@startmail.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/89385
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Srikantha S. Meesala <srikantha@in.ibm.com>
Reviewed-by: RAJA DAS <rajadas2@in.ibm.com>

src/build/parsAndCutElf.py

@@ -6,7 +6,7 @@
 #
 # OpenPOWER sbe Project
 #
-# Contributors Listed Below - COPYRIGHT 2016,2019
+# Contributors Listed Below - COPYRIGHT 2016,2020
 # [+] International Business Machines Corp.
 #
 #
@@ -46,7 +46,7 @@ def parserElf(argv):
     output = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
     i = 0;
     for line in output.stdout:
-        line = line.strip()
+        line = str(line.strip())
 
         if not line: continue