compile failure with current CVS: can only configure for one host and one target at a time

[Duncan Sands]

$ ./configure
...
$ make
...
configure: configuring in gdb.gdbtk
configure: running /bin/sh './configure' --prefix=/usr/local  '--prefix=/usr/local' '--cache-file=./config.cache' '--build=i686-pc-linux-gnu' '--host=i686-pc-linux-gnu' '--target=i686-pc-linux-gnu' '--with-gnu-as' '--with-gnu-ld' '--program-transform-name=s,y,y,' 'CC=gcc' 'CFLAGS=-g -O2' 'LDFLAGS=' 'build_alias=i686-pc-linux-gnu' 'host_alias=i686-pc-linux-gnu' 'target_alias=i686-pc-linux-gnu' '--cache-file=.././config.cache' '--srcdir=.' --cache-file=../.././config.cache --srcdir=.
configure: warning: CC=gcc: invalid host type
configure: warning: CFLAGS=-g -O2: invalid host type
configure: error: can only configure for one host and one target at a time
configure: error: /bin/sh './configure' failed for gdb.gdbtk
configure: error: /bin/sh './configure' failed for testsuite
make: *** [configure-gdb] Error 1