Fix building with Clang on RISC-V

Clang does not have the builtin __builtin_riscv_pause().

Forwarded: MariaDB#3871

Author: ottok

debian/patches/MDEV-36217-Fix-building-with-older-Clang-on-RISC-V.patch

@@ -0,0 +1,25 @@
+From: Jeremie Courreges-Anglas <[email protected]>
+Date: Wed, 5 Mar 2025 16:10:38 -0500
+Subject: Fix building with Clang on RISC-V
+
+Clang does not have the builtin __builtin_riscv_pause().
+
+Forwarded: https://github.com/MariaDB/server/pull/3871
+---
+ include/my_cpu.h | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/include/my_cpu.h
++++ b/include/my_cpu.h
+@@ -97,7 +97,11 @@
+   /* Changed from __ppc_get_timebase for musl and clang compatibility */
+   __builtin_ppc_get_timebase();
+ #elif defined __GNUC__ && defined __riscv
++#ifdef __clang__
++  __asm__ volatile(".long 0x0100000f" ::: "memory");
++#else
+   __builtin_riscv_pause();
++#endif
+ #elif defined __GNUC__
+   /* Mainly, prevent the compiler from optimizing away delay loops */
+   __asm__ __volatile__ ("":::"memory");

debian/patches/series

@@ -7,3 +7,4 @@ fix-reproducible-builds-rocksdb.patch
 mroonga-mrn-lib-dirs-path-reproducible-build.patch
 2006-kfreebsd-amd64.patch
 1063738-revert-c432c9ef.patch
+MDEV-36217-Fix-building-with-older-Clang-on-RISC-V.patch