In the expression returned by the parse_pstats_options function, expand the output of parse_groups (#32)

* In the expression returned by the `parse_pstats_options` function, fully qualify the `parse_groups` function

* Expand the output of `parse_groups` before returning

Co-authored-by: Valentin Churavy <vchuravy@users.noreply.github.com>

---------

Co-authored-by: Valentin Churavy <vchuravy@users.noreply.github.com>

Author: DilumAluthge

src/LinuxPerf.jl

@@ -553,7 +553,7 @@ end
 
 function parse_pstats_options(opts)
     # default events
-    events = :(parse_groups("
+    events = :($parse_groups("
         (cpu-cycles, stalled-cycles-frontend, stalled-cycles-backend),
         (instructions, branch-instructions, branch-misses),
         (task-clock, context-switches, cpu-migrations, page-faults)