Fix: Array index out of bounds warning (#586)
Fix: Array index out of bounds warning (#586)

cppcheck revealed the following errors/warnings:
src/ua_types_encoding_binary.c(49): error (arrayIndexOutOfBounds): Array 'buf[4]' index 4 out of bounds
src/ua_types_encoding_binary.c(49): error (arrayIndexOutOfBounds): Array 'buf[4]' index 5 out of bounds
src/ua_types_encoding_binary.c(50): error (arrayIndexOutOfBounds): Array 'buf[4]' index 6 out of bounds
src/ua_types_encoding_binary.c(50): error (arrayIndexOutOfBounds): Array 'buf[4]' index 7 out of bounds
open62541/open62541,jpfr/open62541,JGrothoff/open62541,jpfr/open62541,AGIsmail/open62541,JGrothoff/open62541,jpfr/open62541,JGrothoff/open62541,open62541/open62541,StalderT/open62541,open62541/open62541,open62541/open62541,JGrothoff/open62541,bostjanv/open62541,bostjanv/open62541,StalderT/open62541,StalderT/open62541,StalderT/open62541,jpfr/open62541,AGIsmail/open62541