UMFPACK: Display timer function used by SuiteSparse_config in report

UMFPACK is built without OpenMP. (It doesn't use it directly.)
Hence, `_OPENMP` is not defined when the UMFPACK libraries are built.

Get the information about the used timer function directly from
SuiteSparse_config.h instead.

Fixes #822.

UMFPACK/Source/umfpack_report_control.c

@@ -14,6 +14,9 @@
 
 #include "umf_internal.h"
 
+#define xstr(s) str(s)
+#define str(s) #s
+
 void UMFPACK_report_control
 (
     const double Control [UMFPACK_CONTROL]
@@ -381,11 +384,7 @@ void UMFPACK_report_control
 
     PRINTF (("    CPU timer: ")) ;
 #ifdef SUITESPARSE_TIMER_ENABLED
-    #ifdef _OPENMP
-        PRINTF (("omp_get_wtime ( )\n")) ;
-    #else
-        PRINTF (("SuiteSparse_time ( )\n")) ;
-    #endif
+    PRINTF (( xstr( SUITESPARSE_TIME ) "\n")) ;
 #else
     PRINTF (("no timer used.\n")) ;
 #endif

UMFPACK/Source/umfpack_report_info.c

@@ -22,6 +22,9 @@
     } \
 }
 
+#define xstr(s) str(s)
+#define str(s) #s
+
 /* RATIO macro uses a double relop, but ignore NaN case: */
 #define RATIO(a,b,c) (((b) == 0) ? (c) : (((double) a)/((double) b)))
 
@@ -160,11 +163,7 @@ void UMFPACK_report_info
 
     PRINTF (("    CPU timer: ")) ;
 #ifdef SUITESPARSE_TIMER_ENABLED
-    #ifdef _OPENMP
-        PRINTF (("omp_get_wtime ( )\n")) ;
-    #else
-        PRINTF (("SuiteSparse_time ( )\n")) ;
-    #endif
+    PRINTF (( xstr( SUITESPARSE_TIME ) "\n")) ;
 #else
     PRINTF (("no timer used.\n")) ;
 #endif