PR6580: Implement symname, symdata and modname context functions.

This adds a couple of the suggested context/stack revamp functions
from PR6580. In particular it replaces the symbolname() function that
sneaked in with the pr6866 branch merge with the suggested symname().

* runtime/sym.c (_stp_mod_sec_lookup): Make section optional.
  (_stp_symbol_snprint): Provide a way to get optional module info.
* tapset/context-symbols.stp: Replace symbolname() with symname(),
  add modname() and symdata().
  (probemod): Implement pc based fallback.
* tapset/context-unwind.stp (caller): Adjust for _stp_symbol_snprint
  change.
* testsuite/systemtap.context/usymbols.exp: Use new symname.
* testsuite/buildok/modname.stp: New test.
* testsuite/buildok/symdata.stp: Likewise.
* testsuite/buildok/symname.stp: Likewise.

1 files changed, 8 insertions, 0 deletions

diff --git a/testsuite/buildok/modname.stp b/testsuite/buildok/modname.stp
new file mode 100755
index 00000000..02229301
--- /dev/null
+++ b/testsuite/buildok/modname.stp
@@ -0,0 +1,8 @@
+#! stap -p4
+#
+# Test the translatability for modname()
+#
+probe begin
+{
+   log(modname(0))
+}