Add support for importing linux "perf script" output (#135)

Fixes #119

sample/programs/cpp/forks.cpp

@@ -0,0 +1,81 @@
+#include <cstdlib>
+#include <unistd.h>
+
+using namespace std;
+
+void alpha()
+{
+  int z = 3;
+  for (int i = 0; i < 100000; i++)
+  {
+    z *= 3;
+  }
+}
+
+void beta()
+{
+  int z = 3;
+  for (int i = 0; i < 100000; i++)
+  {
+    z *= 3;
+  }
+}
+
+void delta()
+{
+  int z = 3;
+  for (int i = 0; i < 100000; i++)
+  {
+    z *= 3;
+  }
+  alpha();
+  beta();
+}
+
+void gamma()
+{
+  int z = 3;
+  for (int i = 0; i < 100000; i++)
+  {
+    z *= 3;
+  }
+}
+
+int main(int argc, char *argv[])
+{
+  pid_t pid1 = fork();
+  if (pid1 == 0)
+  {
+    // Child process 1
+    for (int i = 0; i < 100; i++)
+    {
+      alpha();
+      beta();
+    }
+  }
+  else
+  {
+    pid_t pid2 = fork();
+
+    if (pid2 == 0)
+    {
+      // Child process 2
+      for (int i = 0; i < 100; i++)
+      {
+        alpha();
+        beta();
+      }
+    }
+    else
+    {
+      for (int i = 0; i < 100; i++)
+      {
+        alpha();
+        beta();
+        gamma();
+        delta();
+      }
+    }
+  }
+  return 0;
+}