dev-cpp/elfio: fix build with gcc 15, remove CMake variable

Backport upstream commit [1] to fix build with gcc 15 and get rid of
CMake variable that is obsolete and is not getting used.

[1] https://github.com/serge1/ELFIO/commit/34d2c64

Closes: https://bugs.gentoo.org/881859
Closes: https://bugs.gentoo.org/937460
Signed-off-by: Kostadin Shishmanov <kostadinshishmanov@protonmail.com>
Closes: https://github.com/gentoo/gentoo/pull/41057
Signed-off-by: Sam James <sam@gentoo.org>

dev-cpp/elfio/elfio-3.12.ebuild

@@ -1,4 +1,4 @@
-# Copyright 2020-2023 Gentoo Authors
+# Copyright 2020-2025 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
@@ -20,11 +20,11 @@ DEPEND="test? ( dev-cpp/gtest )"
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-3.12-gnuinstalldirs-docdir.patch
+	"${FILESDIR}"/${PN}-3.12-gcc15.patch
 )
 
 src_configure() {
 	local mycmakeargs=(
-		-DFETCHCONTENT_FULLY_DISCONNECTED=ON
 		-DELFIO_BUILD_TESTS=$(usex test)
 	)
 

dev-cpp/elfio/files/elfio-3.12-gcc15.patch

@@ -0,0 +1,24 @@
+https://bugs.gentoo.org/937460
+
+From 34d2c64237bb40f09879e7421db120e50e7e2923 Mon Sep 17 00:00:00 2001
+From: Orion Poplawski <orion@nwra.com>
+Date: Fri, 31 Jan 2025 20:22:26 -0700
+Subject: [PATCH] Add missing #include <stdint.h> for gcc 15
+
+---
+ elfio/elf_types.hpp | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/elfio/elf_types.hpp b/elfio/elf_types.hpp
+index 3a6850a..cd9aa7f 100644
+--- a/elfio/elf_types.hpp
++++ b/elfio/elf_types.hpp
+@@ -23,6 +23,8 @@ THE SOFTWARE.
+ #ifndef ELFTYPES_H
+ #define ELFTYPES_H
+ 
++#include <stdint.h>
++
+ #ifdef __cplusplus
+ namespace ELFIO {
+ #endif