change the way we found matching tapsets

[Li Guanglei <guanglei at cn dot ibm dot com>]

Hi,
  The syscall table for PowerPC changed from version to version. In 
order to let LKET works for different kernel versions, I have to deal 
with such changes in my tapsets.

  Formerly I usually do that using the conditional preprocessing 
offered by stap. But I found it will become hard to read and will 
become unmaintainable as more kernel versions are involved. For 
example, it's hard to use conditional preprocessing to define the 
following scenario:

  #if arch is ppc64  then
     #if kernel_ver is 2.6.9 then
           probe definitions
     #elseif kernel_ver is 2.6.15.* then
           probe definitions
     #endif
  #elseif arch is i686 then
     ...
  #endif

  So now I am thinking about using different directories for 
different kernel versions. I found that the syscall table stays almost 
the same for each major kernel version, e.g. the syscall table of all 
2.6.15.* are the same. So I want a directory 2.6.15 to handles all 
2.6.15.* versions(including 2.6.15.1, 2.6.15.2 etc).

  But it seems that stap will found in this order:

Searched 'tapsets//2.6.15.4/ppc64/*.stp', match count 0
Searched 'tapsets//2.6.15.4/*.stp', match count 1
Searched 'tapsets//2.6/ppc64/*.stp', match count 0
Searched 'tapsets//2.6/*.stp', match count 0

It won't look at 2.6.15 directory. So can we change the behavior that 
stap search for tapsets, so that I needn't to create the directories 
like 2.6.15.1, 2.6.15.2 etc.