lwip/sys/arch: add inheritance condition in flow control code
lwip/sys/arch: add inheritance condition in flow control code

A compilation error occurs when the PRIORITY_INHERITANCE option is
turned off. This is because the FLOW_CONTROL code uses the function
PRIORITY_INHERITANCE.

Change-Id: Icc3b58e3b9849447078e16fab6754c1ab3e9d193
Signed-off-by: Junhwan Park <7fee488b6f78fc50b291ffc7d10428788977e877@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT