sys-devel/gcc: remove unused patch

Signed-off-by: Michael Mair-Keimberger <mmk@levelnine.at>
Closes: https://github.com/gentoo/gentoo/pull/30997
Signed-off-by: Conrad Kostecki <conikost@gentoo.org>

sys-devel/gcc/files/gcc-13-PR109703-unreachable.patch

@@ -1,54 +0,0 @@
-https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109703
-
-From d50f2599d7b23bdba05a9102645d082ed9bcb05f Mon Sep 17 00:00:00 2001
-From: Kefu Chai <kefu.chai@scylladb.com>
-Date: Mon, 1 May 2023 21:24:26 +0100
-Subject: [PATCH] libstdc++: Set _M_string_length before calling _M_dispose()
- [PR109703]
-
-This always sets _M_string_length in the constructor for ranges of input
-iterators, such as stream iterators.
-
-We copy from the source range to the local buffer, and then repeatedly
-reallocate a larger one if necessary. When disposing the old buffer,
-_M_is_local() is used to tell if the buffer is the local one or not (and
-so must be deallocated). In addition to comparing the buffer address
-with the local buffer, _M_is_local() has an optimization hint so that
-the compiler knows that for a string using the local buffer, there is an
-invariant that _M_string_length <= _S_local_capacity (added for PR109299
-via r13-6915-gbf78b43873b0b7).  But we failed to set _M_string_length in
-the constructor taking a pair of iterators, so the invariant might not
-hold, and __builtin_unreachable() is reached. This causes UBsan errors,
-and potentially misoptimization.
-
-To ensure the invariant holds, _M_string_length is initialized to zero
-before doing anything else, so that _M_is_local() doesn't see an
-uninitialized value.
-
-This issue only surfaces when constructing a string with a range of
-input iterator, and the uninitialized _M_string_length happens to be
-greater than _S_local_capacity, i.e., 15 for the std::string
-specialization.
-
-libstdc++-v3/ChangeLog:
-
-	PR libstdc++/109703
-	* include/bits/basic_string.h (basic_string(Iter, Iter, Alloc)):
-	Initialize _M_string_length.
-
-Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
-Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
-(cherry picked from commit cbf6c7a1d16490a1e63e9a5ce00e9a5c44c4c2f2)
---- a/libstdc++-v3/include/bits/basic_string.h
-+++ b/libstdc++-v3/include/bits/basic_string.h
-@@ -760,7 +760,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
- 	_GLIBCXX20_CONSTEXPR
-         basic_string(_InputIterator __beg, _InputIterator __end,
- 		     const _Alloc& __a = _Alloc())
--	: _M_dataplus(_M_local_data(), __a)
-+	: _M_dataplus(_M_local_data(), __a), _M_string_length(0)
- 	{
- #if __cplusplus >= 201103L
- 	  _M_construct(__beg, __end, std::__iterator_category(__beg));
--- 
-2.31.1