Compile Dhrystone with multiple GCC runs

This doesn't actually make a difference because we had some pragmas in
there to avoid badness, but this sets a better example.

test/benchmarks/dhrystone/check

@@ -28,7 +28,11 @@ echo "ERROR: $march-$mabi failed to run" >$out
 
 tempdir=$(mktemp -d)
 trap "rm -rf $tempdir" EXIT
-$cc ${c[@]} -march=$march -mabi=$mabi -O3 -o $tempdir/dhrystone -static -Wno-all
+for f in ${c[@]}
+do
+  $cc -c $f -march=$march -mabi=$mabi -O3 -fno-common -fno-inline -o $tempdir/$(basename $f).o -static -Wno-all
+done
+$cc -march=$march -mabi=$mabi $tempdir/*.o -o $tempdir/dhrystone
 
 $objdump -d $tempdir/dhrystone > ~/dump
 begin_pc=$($objdump -d $tempdir/dhrystone | grep 'Begin_Time' | grep -e 'sd' -e 'sw' | cut -d: -f1 | xargs echo)

test/benchmarks/dhrystone/dhrystone.h

@@ -391,7 +391,7 @@ extern clock_t	clock();
 	*** You must define HZ!!! ***
 #endif /* HZ */
 #ifndef PASS2
-struct tms      time_info;
+extern struct tms      time_info;
 #endif
 /*extern  int     times ();*/
                 /* see library function "times" */

test/benchmarks/dhrystone/dhrystone_main.c

@@ -7,6 +7,8 @@
 // This is the classic Dhrystone synthetic integer benchmark.
 //
 
+struct tms      time_info;
+
 #define read_csr(reg) ({ unsigned long __tmp; \
   asm volatile ("csrr %0, " #reg : "=r"(__tmp)); \
   __tmp; })