Define TRY_EMPTY_VM_SPACE for riscv64-linux

* config/host-linux.c (TRY_EMPTY_VM_SPACE) [__riscv && __LP64__]:
Define.

gcc/ChangeLog

+2020-03-30  Andreas Schwab  <schwab@suse.de>
+
+	* config/host-linux.c (TRY_EMPTY_VM_SPACE) [__riscv && __LP64__]:
+	Define.
+
 2020-03-30  Will Schmidt  <will_schmidt@vnet.ibm.com>
 
 	* config/rs6000/rs6000-call.c altivec_init_builtins(): Remove code

gcc/config/host-linux.c

@@ -96,6 +96,8 @@
 # define TRY_EMPTY_VM_SPACE	0x8000000000
 #elif defined(__mips__)
 # define TRY_EMPTY_VM_SPACE	0x60000000
+#elif defined(__riscv) && defined (__LP64__)
+# define TRY_EMPTY_VM_SPACE	0x1000000000
 #else
 # define TRY_EMPTY_VM_SPACE	0
 #endif