do notset SUITESPARSE_SPQR_VALID if SUITESPARSE_SPQR_LIBRARY is not valid

cmake/FindSUITESPARSE.cmake

@@ -81,7 +81,9 @@ if( WIN32 )
         PATHS ${SUITESPARSE_LIBRARY_DIRS} )
 	   IF (SUITESPARSE_SPQR_LIBRARY)			
         list ( APPEND SUITESPARSE_LIBRARIES optimized;libspqr;debug;libspqrd)
-	   ENDIF (SUITESPARSE_SPQR_LIBRARY)
+      else(SUITESPARSE_SPQR_LIBRARY)
+        SET(SUITESPARSE_SPQR_VALID FALSE)
+      endif (SUITESPARSE_SPQR_LIBRARY)
     endif()
 
 
@@ -130,7 +132,7 @@ else( WIN32 )
    IF ( SUITESPARSE_LIBRARY_DIR )
 
     # Skipped, as this is set for apple in the block above
-#       if (NOT APPLE)
+    #       if (NOT APPLE)
     list ( APPEND SUITESPARSE_LIBRARIES amd)
     list ( APPEND SUITESPARSE_LIBRARIES btf)
     list ( APPEND SUITESPARSE_LIBRARIES camd)