feat: introduce GCC disable environment variable

This change is to disable the GCC plugin version check for
GCC plugin and CMPLOG, to overcome the issues with incompatability
with expected GCC version and actual GCC version used to compile
using `AFL_GCC_DISABLE_VERSION_CHECK` environment variable.

1 files changed, 4 insertions, 1 deletions

diff --git a/instrumentation/README.gcc_plugin.md b/instrumentation/README.gcc_plugin.md
index 011a574a..34004dc7 100644
--- a/instrumentation/README.gcc_plugin.md
+++ b/instrumentation/README.gcc_plugin.md
@@ -51,7 +51,10 @@ The idea and much of the implementation comes from Laszlo Szekeres.
 In order to leverage this mechanism, you need to have modern enough GCC (>=
 version 4.5.0) and the plugin development headers installed on your system. That
 should be all you need. On Debian machines, these headers can be acquired by
-installing the `gcc-VERSION-plugin-dev` packages.
+installing the `gcc-VERSION-plugin-dev` packages. If you're compiling a GCC 
+plugin that differs from the system-installed version and encounter issues 
+with version checks, you can use the `AFL_GCC_DISABLE_VERSION_CHECK` environment 
+variable.
 
 To build the instrumentation itself, type `make`. This will generate binaries
 called `afl-gcc-fast` and `afl-g++-fast` in the parent directory.