Allocate right amount of space in malloc().
Allocate right amount of space in malloc().

This happened to be just harmless waste of memory, because
sizeof(ParameterInfoClass) > sizeof(ParameterImplClass), but it was clearly
wrong.

Found by Coverity scan.

gavioto/psqlodbc,gavioto/psqlodbc,treasure-data/prestogres-odbc,hlinnaka/psqlodbc,Distrotech/psqlodbc,hlinnaka/psqlodbc,hlinnaka/psqlodbc,gavioto/psqlodbc,Distrotech/psqlodbc,treasure-data/prestogres-odbc,Distrotech/psqlodbc,treasure-data/prestogres-odbc