* configure: Make enable_threads and enable_shared defaults
explicit. Substitute enable_threads into generated Makefiles.
* configure.in: Accept *-*-linux* not just *-*-linux-gnu*.
* libtool.m4: Accept *-*-linux* not just *-*-linux-gnu*.
gcc:
* configure.in: Accept *-*-linux* not just *-*-linux-gnu*.
* fixinc/inclhack.def: Likewise.
* fixinc/mkfixinc.sh: Likewise.
* configure: Regenerate.
* fixinc/fixincl.x: Regenerate.
* install.texi: Document equivalence of linux and linux-gnu.
libio:
* configure.in: Accept *-*-linux* not just *-*-linux-gnu*.
Honor --disable-threads.
libstdc++:
* configure.in: Accept *-*-linux* not just *-*-linux-gnu*.
Honor --disable-threads.
libstdc++-v3:
* configure: Regenerate after change to ../libtool.m4.
libobjc:
* configure: Regenerate after change to ../libtool.m4.