script: project built inside a external directory

the <subproject>-builddir=y option full support
scripts: CFLAGS of projects must point the headers directory

isystem must point on $(sysroot)/usr/include. Sysroot is not automaticly concatenated
scripts: install.mk can pre-install file

like it is possible to define
install-y+=/install/inside/a/directory/myfile.txt
it is possible to define
pre-install-y+=/install/inside/a/directory/myfile.txt

in the second case the file will be installed before the subproject rules.
scripts: call pre-install-y rules
libc: glibc build complete with installation
scripts: define CXX and CXXCPP tools

CXX defined as <CROSS_COMPILE>g++
script: configure inside <builddir>
scripts: define TRIPLET differently than the CROSS_COMPILE

TRIPLET must be defined as <ARCH>-unknown-<KERNEL>-<LIBC><ABI>
tools: install new features

install accepts to install file into directory if -D option is available
scripts: pre-install files into sysroot if requested
database: GNU dbm support
server: nfs-utils uses libtirpc now
server: support of rpcbind without NIS and RQUOTA

rcpbind needs some rpcsvb headers provided by glibc.
But rpcsvc is now obsolete for glibc and sunrpc not supported by other libc.
Libtirpc is the new rpc library but without rpcsvc which are provided by differents RPC server like nfs-utils of nis-utils
server: add NIS/YP support
database: build databases tools
libc: comment about obsolet RPC support into glibc
tools: build rpcgen for host
busybox: new config file for the git version