- section() revamp

- Redirect STDERR for the collection part in both tools
- rm_tempdir in sigtrap
- A part of pt-mysql-summary still depended on the system being run,
  rather than the samples being read. Now it works properly.

t/pt-mysql-summary/pt-mysql-summary.t

@@ -36,7 +36,7 @@ my @files = glob("$dir/*");
 
 is(
    scalar @files,
-   14,
+   15,
    "And leaves all files in there"
 );
 

t/pt-mysql-summary/samples/temp001/mysql-variables

@@ -353,3 +353,4 @@ pt-summary-internal-user   hugmeir@localhost
 pt-summary-internal-FNV_64   Unknown
 pt-summary-internal-trigger_count   0
 pt-summary-internal-symbols   Yes
+pt-summary-internal-pid_file_exists   1

t/pt-mysql-summary/samples/temp002/mysql-variables

@@ -369,3 +369,4 @@ pt-summary-internal-user   hugmeir@localhost
 pt-summary-internal-FNV_64   Unknown
 pt-summary-internal-trigger_count   0
 pt-summary-internal-symbols   Yes
+pt-summary-internal-pid_file_exists   

t/pt-mysql-summary/samples/temp003/mysql-variables

@@ -282,3 +282,4 @@ pt-summary-internal-user   msandbox@%
 pt-summary-internal-FNV_64   Unknown
 pt-summary-internal-trigger_count   0
 pt-summary-internal-symbols   Yes
+pt-summary-internal-pid_file_exists   1

t/pt-mysql-summary/samples/temp004/mysql-variables

@@ -282,3 +282,4 @@ pt-summary-internal-user   msandbox@%
 pt-summary-internal-FNV_64   Unknown
 pt-summary-internal-trigger_count   6
 pt-summary-internal-symbols   No
+pt-summary-internal-pid_file_exists   1

t/pt-mysql-summary/samples/temp005/mysql-variables

@@ -360,3 +360,4 @@ pt-summary-internal-user   msandbox@%
 pt-summary-internal-FNV_64   Unknown
 pt-summary-internal-trigger_count   6
 pt-summary-internal-mysqld_executable_1   Yes
+pt-summary-internal-pid_file_exists   1