darn it, I broke stuff again

- un-gitignore bfd texi files, as they are actually needed as
dependencies for make targets
- bfd: make sure bfd.h is present
- bfd/doc: make sure chew dSYMs get cleaned up
- bfd/m4/ax_patch_libtool_changing_cmd_ifs.m4: make sure libtool exists
before trying to move it
- accidentally deleted some bfd source files... (they might be
regenerate-able, idk...)
- work on tcl.m4
- configure script updates
- gdb/gnulib got broken somehow wrt <string.h>-related `sed`
substitutions, try to fix it
- touch old MPW headers
- opcodes: I broke something wrt i386-opc.lo, try to fix
- utils: recurse into "misc" subdir
- utils/misc/doschk: try to make it safe to include <stdlib.h> (for the
exit() function) by dealing with mismatched malloc() prototype
- zlib: sometimes the ${AR} gets mismatched with the wrong ${ARFLAGS},
try to compensate
- zlib: fix some warnings about implicit function declarations
- etc: add root-gdb-backtrace.sh script from CERN's ROOT package (with
some modifications to silence `shellcheck` warnings)
- add some more texinfo stuff
- add decomment.tproj and relpath.tproj from bootstrap_cmds to utils
(with some modifications)
- zlib: add some files from Apple's zlib fork, such as an
Apple-specific test suite, and an Xcode project

Change-Id: I4c97f86c672b91120bd22f020c214b9a259860d5