Turn 'bool force_collect' parameter to 'ggc_collect' into an 'enum ggc_collect mode'
... to make the meaning more explicit to the reader of the code.
Follow-up to recent commit
0edf2e81bb02cba43b649b3f6e7258b68a779ac0
"Turn global 'ggc_force_collect' variable into 'force_collect' parameter to
'ggc_collect'".
gcc/
* ggc.h (enum ggc_collect): New.
(ggc_collect): Use it.
* ggc-page.c: Adjust.
* ggc-common.c: Likewise.
* ggc-tests.c: Likewise.
* read-rtl-function.c: Likewise.
* selftest-run-tests.c: Likewise.
* doc/gty.texi (Invoking the garbage collector): Likewise.
Suggested-by: David Malcolm <dmalcolm@redhat.com>