tree: Retype variable `programmer_may_write` with bool

Use the bool type instead of an integer for the variable
`programmer_may_write`, since this represents its purpose much better.

Signed-off-by: Felix Singer <felixsinger@posteo.net>
Change-Id: I69958527ae018a92f1c42734a7990d0c532dee0c
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/66885
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71483
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/programmer.h b/programmer.h
index e033c69..24b37fb 100644
--- a/programmer.h
+++ b/programmer.h
@@ -292,7 +292,7 @@
 };
 // FIXME: These need to be local, not global
 extern struct decode_sizes max_rom_decode;
-extern int programmer_may_write;
+extern bool programmer_may_write;
 extern unsigned long flashbase;
 unsigned int count_max_decode_exceedings(const struct flashctx *flash);
 char *extract_programmer_param(const char *param_name);