Problem:      
lack of incoming geometry data validation may 
lead to a server crash when ISCLOSED() function called.

Solution:
necessary incoming data check added.


mysql-test/r/gis.result:
  Fix for BUG#12414917 - ISCLOSED() CRASHES ON 64-BIT BUILDS
    test result.
mysql-test/t/gis.test:
  Fix for BUG#12414917 - ISCLOSED() CRASHES ON 64-BIT BUILDS 
    test case.
sql/spatial.cc:
  Fix for BUG#12414917 - ISCLOSED() CRASHES ON 64-BIT BUILDS 
    check if a LINESTRING has at least one point as we 
  rely on that further.