Increase timeout on riscv64

Some tests are timing out even though they are not stuck. Increase the
timeoutFactor to give them a chance to finish

Relates to adoptium#4976

openjdk/openjdk.mk

@@ -79,12 +79,17 @@ JTREG_BASIC_OPTIONS += -retain:fail,error,*.dmp,javacore.*,heapdump.*,*.trc
 # Ignore tests are not run and completely silent about it
 JTREG_IGNORE_OPTION = -ignore:quiet
 JTREG_BASIC_OPTIONS += $(JTREG_IGNORE_OPTION)
+# riscv64 machines aren't very fast (yet!!)
+ifeq ($(ARCH),riscv64)
+	JTREG_TIMEOUT_OPTION =  -timeoutFactor:16
+else
 # Multiple by 8 the timeout numbers, except on zOS use 2
 ifneq ($(OS),OS/390)
 	JTREG_TIMEOUT_OPTION =  -timeoutFactor:8
 else
 	JTREG_TIMEOUT_OPTION =  -timeoutFactor:2
 endif
+endif
 JTREG_BASIC_OPTIONS += $(JTREG_TIMEOUT_OPTION)
 # Create junit xml
 JTREG_XML_OPTION = -xml:verify