Revert skip-build-config feature.

Cargo.toml

@@ -54,7 +54,6 @@ pyo3-build-config = { path = "pyo3-build-config", version = "0.15.1", features =
 
 [features]
 default = ["macros"]
-skip-build-config = []
 
 # Enables macros: #[pyclass], #[pymodule], #[pyfunction] etc.
 macros = ["pyo3-macros", "indoc", "paste", "unindent"]

build.rs

@@ -172,10 +172,8 @@ fn print_config_and_exit(config: &InterpreterConfig) {
 }
 
 fn main() {
-    if cfg!(not(feature="skip-build-config")) {
-        if let Err(e) = configure_pyo3() {
-            eprintln!("error: {}", e.report());
-            std::process::exit(1)
-        }
+    if let Err(e) = configure_pyo3() {
+        eprintln!("error: {}", e.report());
+        std::process::exit(1)
     }
 }

pyo3-build-config/src/impl_.rs

@@ -32,9 +32,7 @@ pub fn cargo_env_var(var: &str) -> Option<String> {
 /// Gets an external environment variable, and registers the build script to rerun if
 /// the variable changes.
 pub fn env_var(var: &str) -> Option<OsString> {
-    if cfg!(feature = "resolve-config") {
-        println!("cargo:rerun-if-env-changed={}", var);
-    }
+    println!("cargo:rerun-if-env-changed={}", var);
     env::var_os(var)
 }