games-rpg/openglad: fix build with clang

Closes: https://bugs.gentoo.org/830571
Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

games-rpg/openglad/files/openglad-0.98_p20200907-clang.patch

@@ -0,0 +1,10 @@
+Option gets used for C as well leading to gcc warnings and a hard
+error with clang. Option isn't actually needed, so just remove it.
+
+https://bugs.gentoo.org/830571
+--- a/premake4.lua
++++ b/premake4.lua
+@@ -47,3 +47,2 @@
+ 	  defines { "PHYSFS_SUPPORTS_ZIP" }
+-	  buildoptions { "-std=gnu++0x" }
+ 	

games-rpg/openglad/openglad-0.98_p20200907.ebuild

@@ -1,4 +1,4 @@
-# Copyright 1999-2021 Gentoo Authors
+# Copyright 1999-2022 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
@@ -29,6 +29,10 @@ BDEPEND="
 	dev-util/premake:5
 	virtual/pkgconfig"
 
+PATCHES=(
+	"${FILESDIR}"/${P}-clang.patch
+)
+
 src_prepare() {
 	default