bug#19786: 25.0.50; broken build (Attempt to modify RO object)

[Mark Oteiza]

On current HEAD:

In toplevel form:
progmodes/gdb-mi.el:92:1:Error: Attempt to modify read-only object: (error)
Makefile:287: recipe for target 'progmodes/gdb-mi.elc' failed
make[2]: *** [progmodes/gdb-mi.elc] Error 1
make[2]: *** Waiting for unfinished jobs....

In end of data:
progmodes/cc-defs.el:2454:1:Warning: the following functions might not be
    defined at runtime: cc-bytecomp-restore-environment,
    cc-bytecomp-setup-environment, cc-bytecomp-load,
    cc-bytecomp-compiling-or-loading
make[2]: Leaving directory '/tmp/makepkg/emacs-git/src/emacs/lisp'
Makefile:310: recipe for target 'compile-main' failed
make[1]: *** [compile-main] Error 2
make[1]: Leaving directory '/tmp/makepkg/emacs-git/src/emacs/lisp'
Makefile:385: recipe for target 'lisp' failed
make: *** [lisp] Error 2