Fix random build fails on travis/appveyor. Fix #970 
Fix random build fails on travis/appveyor. Fix #970 

flush and fsync amalgamated file
open62541/open62541,JGrothoff/open62541,open62541/open62541,StalderT/open62541,StalderT/open62541,jpfr/open62541,StalderT/open62541,AGIsmail/open62541,jpfr/open62541,AGIsmail/open62541,open62541/open62541,JGrothoff/open62541,jpfr/open62541,JGrothoff/open62541,open62541/open62541,bostjanv/open62541,jpfr/open62541,StalderT/open62541,bostjanv/open62541,JGrothoff/open62541