[PATCH,FORTRAN] Fix memory leak of gsymbol

[Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>]

Hi!

Regtested on x86_64-unknown-linux, installing on
aldot/fortran-fe-stringpool.

We did not free global symbols. For a simplified abstract_type_3.f03
valgrind reports:

96 bytes in 1 blocks are still reachable in loss record 461 of 602
   at 0x48377D5: calloc (vg_replace_malloc.c:711)
   by 0x21257C3: xcalloc (xmalloc.c:162)
   by 0x98611B: gfc_get_gsymbol(char const*) (symbol.c:4341)
   by 0x932C58: parse_module() (parse.c:5912)
   by 0x9336F8: gfc_parse_file() (parse.c:6236)
   by 0x991449: gfc_be_parse_file() (f95-lang.c:204)
   by 0x11D8EDE: compile_file() (toplev.c:455)
   by 0x11DB9C3: do_compile() (toplev.c:2170)
   by 0x11DBCAF: toplev::main(int, char**) (toplev.c:2305)
   by 0x2045D37: main (main.c:39)

This patch reduces leaks to

 LEAK SUMMARY:
    definitely lost: 344 bytes in 1 blocks
    indirectly lost: 3,024 bytes in 4 blocks
      possibly lost: 0 bytes in 0 blocks
-   still reachable: 1,576,174 bytes in 2,277 blocks
+   still reachable: 1,576,078 bytes in 2,276 blocks
         suppressed: 0 bytes in 0 blocks

gcc/fortran/ChangeLog:

2018-10-21  Bernhard Reutner-Fischer  <aldot@gcc.gnu.org>

	* parse.c (clean_up_modules): Free gsym.
---
 gcc/fortran/parse.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/gcc/fortran/parse.c b/gcc/fortran/parse.c
index b7265c42f58..f7c369a17ac 100644
--- a/gcc/fortran/parse.c
+++ b/gcc/fortran/parse.c
@@ -6066,7 +6066,7 @@ resolve_all_program_units (gfc_namespace *gfc_global_ns_list)
 
 
 static void
-clean_up_modules (gfc_gsymbol *gsym)
+clean_up_modules (gfc_gsymbol *&gsym)
 {
   if (gsym == NULL)
     return;
@@ -6074,14 +6074,18 @@ clean_up_modules (gfc_gsymbol *gsym)
   clean_up_modules (gsym->left);
   clean_up_modules (gsym->right);
 
-  if (gsym->type != GSYM_MODULE || !gsym->ns)
+  if (gsym->type != GSYM_MODULE)
     return;
 
-  gfc_current_ns = gsym->ns;
-  gfc_derived_types = gfc_current_ns->derived_types;
-  gfc_done_2 ();
-  gsym->ns = NULL;
-  return;
+  if (gsym->ns)
+    {
+      gfc_current_ns = gsym->ns;
+      gfc_derived_types = gfc_current_ns->derived_types;
+      gfc_done_2 ();
+      gsym->ns = NULL;
+    }
+  free (gsym);
+  gsym = NULL;
 }
 
 
-- 
2.19.1