Fix tests for pt-mysql-summary

$ prove -vw --trap --timer t/pt-mysql-summary
[18:34:53] t/pt-mysql-summary/pt-mysql-summary.t ............. 
1..0 # SKIP Keyring plugins are enabled.
skipped: Keyring plugins are enabled.
[18:34:53] t/pt-mysql-summary/pt-mysql-summary_encryption.t .. grep: /proc/1850/environ: Permission denied

ok 1 - Using --save-samples doesn't mistakenly delete the target dir
ok 2 - And leaves all files in there
ok 3 - --databases works
ok 4 - InnoDB section present
ok 5 - Security works
grep: /proc/1850/environ: Permission denied
not ok 6 - --read-samples works for t/pt-mysql-summary/temp_enc002

#   Failed test '--read-samples works for t/pt-mysql-summary/temp_enc002'
#   at t/pt-mysql-summary/pt-mysql-summary_encryption.t line 106.
# 131c131
# <                      Size | 16,0M
# ---
# >                      Size | 16.0M
# 188c188
# <          Buffer Pool Size | 128,0M
# ---
# >          Buffer Pool Size | 128.0M
# 193c193
# <             Log File Size | 2 * 5,0M = 10,0M
# ---
# >             Log File Size | 2 * 5.0M = 10.0M
# 219c219
# <                 Key Cache | 16,0M
# ---
# >                 Key Cache | 16.0M
# 244c244
# <        bulk_insert_buffer | 0,00
# ---
# >        bulk_insert_buffer | 0.00
grep: /proc/1850/environ: Permission denied
not ok 7 - --read-samples works for t/pt-mysql-summary/temp_enc003
...
grep: /proc/1850/environ: Permission denied
not ok 8 - --read-samples works for t/pt-mysql-summary/temp_enc004
...
grep: /proc/1850/environ: Permission denied
not ok 9 - --read-samples works for t/pt-mysql-summary/temp_enc005
...
grep: /proc/1850/environ: Permission denied
not ok 10 - --read-samples works for t/pt-mysql-summary/temp_enc006
...
grep: /proc/1850/environ: Permission denied
not ok 11 - --read-samples works for t/pt-mysql-summary/temp_enc007
...
not ok 14 - Keyring plugins included in report

#   Failed test 'Keyring plugins included in report'
#   at t/pt-mysql-summary/pt-mysql-summary_encryption.t line 138.
...
not ok 15 - Encrypted tables included in report

#   Failed test 'Encrypted tables included in report'
#   at t/pt-mysql-summary/pt-mysql-summary_encryption.t line 144.
...
not ok 16 - Encrypted tablespaces included in report

#   Failed test 'Encrypted tablespaces included in report'
#   at t/pt-mysql-summary/pt-mysql-summary_encryption.t line 150.
...
Test Summary Report
-------------------
t/pt-mysql-summary/pt-mysql-summary_encryption.t (Wstat: 2304 Tests: 16 Failed: 9)
  Failed tests:  6-11, 14-16
  Non-zero exit status: 9
Files=2, Tests=16, 28 wallclock secs ( 0.02 usr  0.01 sys +  8.62 cusr  7.83 csys = 16.48 CPU)
Result: FAIL