Fix atomic detection for RISC-V (riscv64)

See:
abe2e7de4d
https://bugs.ruby-lang.org/issues/16800
https://bugs.ruby-lang.org/issues/16774

Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>

abe2e7de4d1f2d5861d7c9ab9c7e778f2ee1dcd2.patch

@@ -0,0 +1,37 @@
+From abe2e7de4d1f2d5861d7c9ab9c7e778f2ee1dcd2 Mon Sep 17 00:00:00 2001
+From: Andreas Schwab <schwab@suse.de>
+Date: Fri, 10 Apr 2020 15:34:52 +0200
+Subject: [PATCH] Don't require sub-word atomics
+
+On some architectures (like RISC-V) sub-word atomics are only available
+when linking against -latomic, but the configure script doesn't do that,
+causing the atomic checks to fail and the resulting ruby binary is
+non-functional.  Ruby does not use sub-word atomic operations, rb_atomic_t
+is defined to unsigned int, so use unsigned int when checking for atomic
+operations.
+---
+ configure.ac | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 7c12b9e5fb94..ba86deffbebb 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -1498,7 +1498,7 @@ AS_IF([test "$GCC" = yes], [
+     ])
+ 
+     AC_CACHE_CHECK([for __atomic builtins], [rb_cv_gcc_atomic_builtins], [
+-	AC_TRY_LINK([unsigned char atomic_var;],
++	AC_TRY_LINK([unsigned int atomic_var;],
+ 		    [
+ 			__atomic_exchange_n(&atomic_var, 0, __ATOMIC_SEQ_CST);
+ 			__atomic_exchange_n(&atomic_var, 1, __ATOMIC_SEQ_CST);
+@@ -1513,7 +1513,7 @@ AS_IF([test "$GCC" = yes], [
+     ])
+ 
+     AC_CACHE_CHECK([for __sync builtins], [rb_cv_gcc_sync_builtins], [
+-	AC_TRY_LINK([unsigned char atomic_var;],
++	AC_TRY_LINK([unsigned int atomic_var;],
+ 		    [
+ 			__sync_lock_test_and_set(&atomic_var, 0);
+ 			__sync_lock_test_and_set(&atomic_var, 1);

ruby-2.6.5-disable-assert.patch

@@ -1,13 +0,0 @@
-diff --git a/thread_pthread.c b/thread_pthread.c
-index 670e917..d466d10 100644
---- a/thread_pthread.c
-+++ b/thread_pthread.c
-@@ -1992,7 +1992,7 @@ rb_sigwait_fd_put(const rb_thread_t *th, int fd)
- 
-     VM_ASSERT(signal_self_pipe.normal[0] == fd);
-     old = ATOMIC_PTR_EXCHANGE(sigwait_th, THREAD_INVALID);
--    if (old != th) assert(old == th);
-+    /* if (old != th) assert(old == th); */
- }
- 
- #ifndef HAVE_PPOLL

ruby.spec

@@ -160,7 +160,7 @@ Patch13: ruby-2.8.0-remove-unneeded-gem-require-for-ipaddr.patch
 Patch22: ruby-2.6.0-config-support-include-directive.patch
 
 # Disable pthread assert on Linux RISC-V (riscv64)
-Patch30: ruby-2.6.5-disable-assert.patch
+Patch30: abe2e7de4d1f2d5861d7c9ab9c7e778f2ee1dcd2.patch
 
 Requires: %{name}-libs%{?_isa} = %{version}-%{release}
 Suggests: rubypick