LikewiseOpen creates user names with a backslash in them. A gentle
massage with sed(1) allows such strings to be inserted into build.h
properly quoted. I am also adding the same for host name and other
strings used in the script that are more or less user-controlled.
ASTERISK-26754
Change-Id: Iac5ef2b67a68ee58f35ddbf86bb818ba6eabecae