gcc: fix hidden weak symbols by removing buggy gcc patch

We are noticing the presence of the following patch in various
openembedded gcc versions:

0024-PR-target-32219.patch

However, contrarily to its "Backport" status, that patch is
not upstream in gcc, and it breaks handling of start/stop automatic
weak hidden symbols we use in lttng-ust.

We are only experiencing problems on the various openembedded
compilers, but on no other distro (with same compiler versions),
which led us to suspect a buggy distro-specific gcc patch.

We've been testing with openembedded gcc-4.9.2-r0. Rebuilding the gcc
compiler with this patch removed fixes the lttng-ust issue.

Link: http://lists.openembedded.org/pipermail/openembedded-core/2016-January/116306.html
Link: http://lists.lttng.org/pipermail/lttng-dev/2014-May/023112.html
Link: https://gcc.gnu.org/ml/gcc-help/2014-05/msg00042.html
Link: http://cgit.openembedded.org/openembedded-core/commit/?id=3cb2b003db7371b3a47d02c08352a262e1e419b4
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=15435

(From OE-Core rev: 3e98ba4d6c1d1e4919ce373ec031d41c2538f10b)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/gcc/gcc-4.9.inc

@@ -47,7 +47,6 @@ SRC_URI = "\
     file://0021-gcc-disable-MASK_RELAX_PIC_CALLS-bit.patch \
     file://0022-COLLECT_GCC_OPTIONS.patch \
     file://0023-Use-the-defaults.h-in-B-instead-of-S-and-t-oe-in-B.patch \
-    file://0024-PR-target-32219.patch \
     file://0025-fortran-cross-compile-hack.patch \
     file://0026-libgcc-sjlj-check.patch \
     file://0027-cpp-honor-sysroot.patch \

meta/recipes-devtools/gcc/gcc-4.9/0024-PR-target-32219.patch

@@ -1,62 +0,0 @@
-From e0d15f4f8bf28c351b9215ca37f1caa24df0e1fd Mon Sep 17 00:00:00 2001
-From: Khem Raj <raj.khem@gmail.com>
-Date: Fri, 29 Mar 2013 09:18:54 +0400
-Subject: [PATCH 24/35] PR target/32219
-
-* varasm.c (default_binds_local_p_1): Weak data is not local.
-
-Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
-Signed-off-by: Khem Raj <raj.khem@gmail.com>
-
-Upstream-Status: Backport
----
- gcc/testsuite/gcc.dg/visibility-21.c |   14 ++++++++++++++
- gcc/varasm.c                         |    9 ++++-----
- 2 files changed, 18 insertions(+), 5 deletions(-)
- create mode 100644 gcc/testsuite/gcc.dg/visibility-21.c
-
-Index: gcc-4.9-20140316/gcc/varasm.c
-===================================================================
---- gcc-4.9-20140316.orig/gcc/varasm.c
-+++ gcc-4.9-20140316/gcc/varasm.c
-@@ -6771,6 +6771,10 @@ default_binds_local_p_1 (const_tree exp,
-   /* Static variables are always local.  */
-   else if (! TREE_PUBLIC (exp))
-     local_p = true;
-+  /* hidden weak can't be overridden by something non-local, all
-+     that is possible is that it is not defined at all. */
-+  else if (DECL_WEAK (exp))
-+    local_p = false;
-   /* A variable is local if the user has said explicitly that it will
-      be.  */
-   else if ((DECL_VISIBILITY_SPECIFIED (exp)
-@@ -6784,11 +6788,6 @@ default_binds_local_p_1 (const_tree exp,
-      local.  */
-   else if (DECL_VISIBILITY (exp) != VISIBILITY_DEFAULT)
-     local_p = true;
--  /* Default visibility weak data can be overridden by a strong symbol
--     in another module and so are not local.  */
--  else if (DECL_WEAK (exp)
--	   && !resolved_locally)
--    local_p = false;
-   /* If PIC, then assume that any global name can be overridden by
-      symbols resolved from other modules.  */
-   else if (shlib)
-Index: gcc-4.9-20140316/gcc/testsuite/gcc.dg/visibility-22.c
-===================================================================
---- /dev/null
-+++ gcc-4.9-20140316/gcc/testsuite/gcc.dg/visibility-22.c
-@@ -0,0 +1,13 @@
-+/* PR target/32219 */
-+/* { dg-do run } */
-+/* { dg-require-visibility "" } */
-+/* { dg-options "-fPIC" { target fpic } } */
-+
-+extern void f() __attribute__((weak,visibility("hidden")));
-+extern int puts( char const* );
-+int main()
-+{
-+  if (f)
-+    f();
-+  return 0;
-+}