gnu: cgdb: Reference gdb.

* gnu/packages/debug.scm (cgdb)[inputs]: Add gdb, bash-minimal
[arguments]: Add phase to fix hardcoded gdb and sh paths
Add configure flags for cross-compilation

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/debug.scm

@@ -760,9 +760,25 @@ (define-public cgdb
         (base32 "1w8ib2vg3pg68d9hh97fw5042c73i9nqavdddc87n9bpscjbaf0d"))))
     (build-system gnu-build-system)
     (inputs
-     (list ncurses readline))
+     (list bash-minimal ncurses readline gdb))
     (native-inputs
      (list flex texinfo))
+    (arguments
+     `(#:configure-flags
+        (list
+          (string-append "ac_cv_rl_version=" ,(package-version readline))
+          "ac_cv_file__dev_ptmx=no"
+          "ac_cv_file__proc_self_status=no"
+          "ac_cv_func_setpgrp_void=no")
+       #:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'fix-paths
+           (lambda* (#:key inputs #:allow-other-keys)
+             (let ((gdb (search-input-file inputs "bin/gdb"))
+                   (sh (search-input-file inputs "bin/sh")))
+               (substitute* "lib/util/fork_util.cpp"
+                 (("GDB = \"gdb\"") (string-append "GDB = \"" gdb "\"")))
+               (substitute* "cgdb/cgdb.cpp" (("/bin/sh") sh))))))))
     (home-page "https://cgdb.github.io")
     (synopsis "Console front-end to the GNU debugger")
     (description