port to firehose-0.3

import firehose.model instead of firehose.report
to_xml_bytes instead to_xml_string
update dependencies in mock

use python-subprocess32 from distribution
add python-six
newer versions of firehose and gccinvocation
clang-analyzer workaround
fakegcc: do not write to stderr

configure scripts don't like it:

$ diff -u config.log-realgcc config.log-fakegcc
 configure:10854: checking if gcc PIC flag -fPIC -DPIC works
 configure:10872: gcc -c -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -grecord-gcc-switches  -m64 -mtune=generic  -fPIC -DPIC -DPIC conftest.c >&5
 configure:10876: $? = 0
-configure:10889: result: yes
+configure:10889: result: no

Comment in the generated configure script:

  The compiler can only warn and ignore the option if not recognized
  So say no if there are warnings other than the usual output.
do not die if source file cannot be found

E.g. configure creates conftest.c and then deletes it, multiple times.
With this patch such reports are created without the hexdigest attribute
-- perhaps we better delete them altogether?
Merge pull request #1 from mmilata/f19-fixes

F19 fixes