Defines starting with `b' in src/slirp

• BOOTP_CLIENT src/slirp/bootp.h:10
• BOOTP_REPLY src/slirp/bootp.h:13
• BOOTP_REQUEST src/slirp/bootp.h:12
• BOOTP_SERVER src/slirp/bootp.h:9
• BOOTP_VEND_NEXT src/slirp/bootp.h:6
• BOOTP_VENDOR_LEN src/slirp/bootp.h:96