Solidity fixes.

libsolidity/Compiler.cpp

@@ -375,7 +375,7 @@ bool Compiler::visit(FunctionDefinition const& _function)
 	for (VariableDeclaration const* localVariable: _function.getLocalVariables())
 		m_context.removeVariable(*localVariable);
 
-	m_context.adjustStackOffset(-c_returnValuesSize);
+	m_context.adjustStackOffset(-(int)c_returnValuesSize);
 	if (!_function.isConstructor())
 		m_context << eth::Instruction::JUMP;
 	return false;

libsolidity/CompilerContext.cpp

@@ -63,7 +63,7 @@ void CompilerContext::addVariable(VariableDeclaration const& _declaration,
 
 void CompilerContext::removeVariable(VariableDeclaration const& _declaration)
 {
-	solAssert(m_localVariables.count(&_declaration), "");
+	solAssert(!!m_localVariables.count(&_declaration), "");
 	m_localVariables.erase(&_declaration);
 }