dev-lang/swift: remove dev-cpp/tbb as a strong blocker for Swift 6

Swift 6 builds with `dev-cpp/tbb` installed on systems with
>=libstdc++-11 (the minimum version currently supported by Gentoo) as
long as it's bootstrapped by swift-5.10.1-r3 or later (which has a patch
backported from Swift 6 which prevents `<execution>` from getting picked
up).

Bug: https://bugs.gentoo.org/947141
Signed-off-by: Itai Ferber <itai@itaiferber.net>

dev-lang/swift/swift-6.0.2.ebuild

@@ -93,6 +93,7 @@ BDEPEND="
 	>=dev-util/patchelf-0.18
 	>=dev-vcs/git-2.39
 	>=sys-apps/coreutils-9
+	>=sys-devel/gcc-11
 	>=sys-libs/ncurses-6
 	>=sys-libs/zlib-1.3
 	|| (
@@ -109,18 +110,6 @@ BDEPEND="
 	' python3_{12..13})
 "
 
-# Swift 6 upstream currently doesn't build with oneTBB installed because Swift's
-# `libstdcxx.h` includes `<execution>`, which, in combination with recent
-# `libstdc++` versions, causes `tbb/execution` to get picked up; this results in
-# a circular dependency back on the stdlib, failing the build.
-#
-# See:
-# * https://bugs.gentoo.org/947141
-# * https://github.com/swiftlang/swift/issues/76166
-BDEPEND+="
-	!!dev-cpp/tbb
-"
-
 # Adapted from `flag-o-matic.eclass`'s `raw-ldflags`: turns GCC-style flags
 # (`-Wl,-foo`) into Clang-style flags (`-Xlinker -foo`).
 clang-ldflags() {