Incorrect C value category parsing

[Suzukaze7]

Some value category parsing logic is different from cppreference.

For example, assignment operators and comma operators are prvalue.

Non-lvalue object expressions

The following expressions are non-lvalue object expressions:

• integer, character, and floating constants
• all operators not specified to return lvalues, including
  • any function call expression
  • any cast expression (note that compound literals, which look similar, are lvalues)
  • member access operator (dot) applied to a non-lvalue structure/union, f().x, (x, s1).a, (s1 = s2).m
  • results of all arithmetic, relational, logical, and bitwise operators
  • results of increment and decrement operators (note: pre-forms are lvalues in C++)
  • results of assignment operators (note: also lvalues in C++)
  • the conditional operator (note: is lvalue in C++ if both the second and third operands are lvalues of the same type)
  • the comma operator (note: is lvalue in C++ if the second operand is)
  • the address-of operator, even if neutralized by application to the result of unary * operator

But in cdt, they are lvalue or conditional lvalue.

cdt/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/c/CASTBinaryExpression.java

Lines 274 to 290 in c63f988

	public boolean isLValue() {
	switch (getOperator()) {
	case op_assign:
	case op_binaryAndAssign:
	case op_binaryOrAssign:
	case op_binaryXorAssign:
	case op_divideAssign:
	case op_minusAssign:
	case op_moduloAssign:
	case op_multiplyAssign:
	case op_plusAssign:
	case op_shiftLeftAssign:
	case op_shiftRightAssign:
	return true;
	}
	return false;
	}

cdt/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/c/CASTExpressionList.java

Lines 120 to 128 in c63f988

	@Override
	public boolean isLValue() {
	for (int i = expressions.length - 1; i >= 0; i--) {
	IASTExpression expr = expressions[i];
	if (expr != null)
	return expr.isLValue();
	}
	return false;
	}