Crate is rebuilt on every build due to rerun-if-env-changed

[joehoyle]

As mentioned in #210 (comment), every time I run cargo check etc then the ext-php-rs build script is run, due to the use of rerun-if-env-changed.

I tracked it down specifically to the PATH env var -- PHP and PHP_CONFIG don't cause issues (though those env vars are not set). My $PATH is stable, so it's not like it's changing. (unless the build script it's self is setting something).

[rmccue]

Ran through debugging this with @joehoyle, this actually turns out to be due to:

ext-php-rs/build.rs

Line 240 in e6afecb

println!("cargo:rerun-if-changed=Cargo.lock");

When this crate is loaded as a dependency, there's no local Cargo.lock (as it's in the root crate instead); this causes it to rebuild every time due to rust-lang/cargo#6003

[ptondereau]

Ran through debugging this with @joehoyle, this actually turns out to be due to:

ext-php-rs/build.rs

Line 240 in e6afecb

println!("cargo:rerun-if-changed=Cargo.lock");

When this crate is loaded as a dependency, there's no local Cargo.lock (as it's in the root crate instead); this causes it to rebuild every time due to rust-lang/cargo#6003

I've introduced that cargo flag recently, but I forgot to remove it. If you have the time, feel free to submit a PR to remove it! I'll be glad to merge it quickly. Thank you for this investigation

[rmccue]

Should we retain it behind a flag? Might be useful for debugging/development purposes.

[ptondereau]

Should we retain it behind a flag? Might be useful for debugging/development purposes.

Let just remove it for the moment and see later if we can provide a better solution