Disable LLVM/Clang for riscv64

+FATAL:  fatal llvm error: Cannot select: 0x2aabd9ebd0: ch = brcond 0x2aabd9f6c8, 0x2aabd9f5f8, BasicBlock:ch<b.op.1.start 0x2aabdfc530>
+  0x2aabd9f5f8: i64 = setcc 0x2aabd9f8d0, Constant:i64<0>, setne:ch
+    0x2aabd9f8d0: i64,ch = load<(load 2 from %ir.6), zext from i16> 0x2aabdc9b48, 0x2aabd9f3f0, undef:i64
+      0x2aabd9f3f0: i64 = add nuw 0x2aabd9ee40, Constant:i64<6>
+        0x2aabd9ee40: i64,ch = load<(load 8 from %ir.3)> 0x2aabdc9b48, 0x2aabd9ed08, undef:i64
+          0x2aabd9ed08: i64 = add nuw 0x2aabd9eb68, Constant:i64<8>
+            0x2aabd9eb68: i64,ch = CopyFromReg 0x2aabdc9b48, Register:i64 %13
+              0x2aabd9eb00: i64 = Register %13
+            0x2aabd9eca0: i64 = Constant<8>
+          0x2aabd9edd8: i64 = undef
+        0x2aabd9f388: i64 = Constant<6>
+      0x2aabd9edd8: i64 = undef
+    0x2aabd9f528: i64 = Constant<0>
+In function: evalexpr_0_0
+server closed the connection unexpectedly
+	This probably means the server terminated abnormally
+	before or while processing the request.
+connection to server was lost
RPM build errors:
+ test 1 -eq 0

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

postgresql.spec

@@ -32,7 +32,12 @@
 %{!?beta:%global beta 0}
 
 %{!?test:%global test 1}
+%ifnarch riscv64
 %{!?llvmjit:%global llvmjit 1}
+%else
+# Fail to pass tests on riscv64
+%{!?llvmjit:%global llvmjit 0}
+%endif
 %{!?upgrade:%global upgrade 1}
 %{!?plpython:%global plpython 1}
 %{!?plpython3:%global plpython3 1}
@@ -1266,6 +1271,7 @@ make -C postgresql-setup-%{setup_version} check
 %changelog
 * Sun Apr 05 2020 David Abdurachmanov <david.abdurachmanov@sifive.com> - 12.2-2.0.riscv64
 - Disable spinlocks on RISC-V 64-bit (riscv64)
+- Disable LLVM/Clang for riscv64 (fails tests)
 
 * Thu Mar 12 2020 Patrik Novotný <panovotn@redhat.com> - 12.2-2
 - Fix requirements for JIT in postgresql-server-devel