jit: Add missing type-checking to gcc_jit_{l|r}value_access_field

jit: Add missing type-checking to gcc_jit_{l|r}value_access_field

gcc/jit/ChangeLog:
	* libgccjit.c (gcc_jit_lvalue_access_field): Verify that the field
	is for the correct struct.
	(gcc_jit_rvalue_access_field): Likewise.

gcc/testsuite/ChangeLog:
	* jit.dg/test-error-accessing-field-in-other-struct.c: Rename to...
	* jit.dg/test-error-gcc_jit_rvalue_dereference_field-wrong-struct.c:
	...this.
	* jit.dg/test-error-gcc_jit_lvalue_access_field-wrong-struct.c:
	New testcase.
	* jit.dg/test-error-gcc_jit_rvalue_access_field-wrong-struct.c:
	New testcase.

From-SVN: r224565