dev-cpp/tbb: fix underlinking on musl

Avoid *context APIs.

In theory, may not be needed (shouldn't be) given we've fixed our packaging
of libucontext, but let's do this anyway as the fix is upstream, and it
avoids possible otehr issues.

Bug: rui314/mold#281
Closes: https://bugs.gentoo.org/832700
Signed-off-by: Sam James <[email protected]>

dev-cpp/tbb/files/tbb-2021.5.0-musl-setcontext.patch

@@ -0,0 +1,30 @@
+https://bugs.gentoo.org/832700
+https://github.com/oneapi-src/oneTBB/commit/6a15b64093c51ddc00bdf4a6b49d4bbec1574a12
+
+From: Rui Ueyama <[email protected]>
+Date: Fri, 4 Feb 2022 19:32:11 +0900
+Subject: [PATCH] Make tbb compile with musl libc (#748)
+
+TBB resumable tasks are implemented using getcontext() and setcontext()
+on Unix-like systems. These functions are deprecated in the recent
+versions of POSIX and may not exist. musl libc does not provide these
+functions.
+
+There's unfortunately no way to detect musl (musl intentionally do not
+define macros like `__MUSL__`), so __TBB_RESUMABLE_TASKS is defined if
+`__GLIBC__`. glibc-compatible libc's such as uClibc defines `__GLIBC__`,
+so it should work as a catch-all condition.
+
+Signed-off-by: Rui Ueyama <[email protected]>
+--- a/include/oneapi/tbb/detail/_config.h
++++ b/include/oneapi/tbb/detail/_config.h
+@@ -268,7 +268,7 @@
+     #define __TBB_CPP20_COMPARISONS_PRESENT __TBB_CPP20_PRESENT
+ #endif
+
+-#define __TBB_RESUMABLE_TASKS                           (!__TBB_WIN8UI_SUPPORT && !__ANDROID__ && !__QNXNTO__)
++#define __TBB_RESUMABLE_TASKS                           (!__TBB_WIN8UI_SUPPORT && !__ANDROID__ && !__QNXNTO__ && (!__linux__ || __GLIBC__))
+
+ /* This macro marks incomplete code or comments describing ideas which are considered for the future.
+  * See also for plain comment with TODO and FIXME marks for small improvement opportunities.
+

dev-cpp/tbb/tbb-2021.5.0.ebuild → dev-cpp/tbb/tbb-2021.5.0-r1.ebuild

@@ -30,6 +30,8 @@ PATCHES=(
 	"${FILESDIR}"/${PN}-2021.4.0-missing-TBB_machine_fetchadd4.patch
 	# need to verify this is in master
 	"${FILESDIR}"/${PN}-2021.5.0-musl-mallinfo.patch
+	# musl again, should be in.. 2022?
+	"${FILESDIR}"/${PN}-2021.5.0-musl-setcontext.patch
 )
 
 src_configure() {