Work around AIX shell builtin printf not handling \NNN.

On AIX, ksh builtin printf does not understand \NNN. Some tests use this
to generate test data, and so fail on AIX. Rework these tests to use python
to generate the correct characters. This fixes the tests on AIX and should
be more generally portable.

tests/test-highlight

@@ -119,7 +119,7 b' cd ..'
 hg init eucjp
 cd eucjp
 
-printf '\265\376\n' >> eucjp.txt  # Japanese kanji "Kyo"
+python -c 'print("\265\376")' >> eucjp.txt  # Japanese kanji "Kyo"
 
 hg ci -Ama
 

tests/test-patchbomb

@@ -170,7 +170,7 b" hg email --date '1970-1-1 0:1' -n --flag"
  -c bar -s test -r 0:1 | fixheaders
 
 echo "% test multi-byte domain parsing"
-UUML=`printf '\374'`
+UUML=`python -c 'import sys; sys.stdout.write("\374")'`
 HGENCODING=iso-8859-1
 export HGENCODING
 hg email --date '1980-1-1 0:1' -m tmp.mbox -f quux -t "bar@${UUML}nicode.com" \