add a export-symbols feature flag

Author: folkertdev

libz-rs-sys-cdylib/Cargo.toml

@@ -23,7 +23,7 @@ semver-prefix = ["libz-rs-sys/semver-prefix"] # prefix all symbols in a semver-c
 capi = []
 
 [dependencies]
-libz-rs-sys = { version = "0.4.2", path = "../libz-rs-sys", default-features = false }
+libz-rs-sys = { version = "0.4.2", path = "../libz-rs-sys", default-features = false, features = ["export-symbols"] }
 
 [package.metadata.capi.library]
 version = "1.3.0" # the zlib api version we match

libz-rs-sys/Cargo.toml

@@ -15,9 +15,10 @@ default = ["std", "rust-allocator"] # when used as a rust crate, use the rust al
 c-allocator = ["zlib-rs/c-allocator"] # by default, use malloc/free for memory allocation
 rust-allocator = ["zlib-rs/rust-allocator"] # by default, use the rust global alloctor for memory allocation
 std = ["zlib-rs/std"] # assume `::std` is available
-custom-prefix = [] # use the LIBZ_RS_SYS_PREFIX to prefix all exported symbols
-testing-prefix = [] # prefix all symbols with LIBZ_RS_SYS_TEST_ for testing
-semver-prefix = [] # prefix all symbols in a semver-compatible way
+export-symbols = [] # whether the zlib api symbols are publicly exported
+custom-prefix = ["export-symbols"] # use the LIBZ_RS_SYS_PREFIX to prefix all exported symbols
+testing-prefix = ["export-symbols"] # prefix all symbols with LIBZ_RS_SYS_TEST_ for testing
+semver-prefix = ["export-symbols"] # prefix all symbols in a semver-compatible way
 
 [dependencies]
 zlib-rs = { workspace = true, default-features = false }