build & host

Nope. See `info standards' for the definition of $build*, $host* and
$target* macros. Basically, $build* refer to the system compilation is
being performed on, $host* refer to the system compiled binaries are to
run on and $target* refer to the system compiled binaries will handle. As
such $target* usually have a meaning a meaning for developemt tool only.

So far packages that make use of $target* I know of are binutils, gcc,
gdb and ksymoops (a Linux run-time error disassembler). Let's take
binutils as an example. I compile it in several ways, following are
examples of configure invocations:

1. `./configure --build=mipsel-linux --host=mipsel-linux
--target=mipsel-linux' will build native mipsel-linux binutils on
mipsel-linux.

2. `./configure --build=i386-linux --host=mipsel-linux
--target=mipsel-linux' will cross-build native mipsel-linux binutils on
i386-linux.

3. `./configure --build=i386-linux --host=i386-linux
--target=mipsel-linux' will build mipsel-linux cross-binutils on
i386-linux.

4. `./configure --build=mipsel-linux --host=i386-linux
--target=mipsel-linux' will cross-build mipsel-linux cross-binutils for
i386-linux on mipsel-linux.

As you see, only if $build != $host a cross-compilation is performed.