Make it compile, at least.

Since last commit, Rust changed the behavior of `extern static`; see
rust-lang/rust#35112

In the future, this should be change to an unsafe block, but now it suffices to turn off the error by the `#[allow(...)]` switch.

libhdf5-sys/src/h5e.rs

@@ -71,6 +71,7 @@ extern {
 
 pub use self::globals::*;
 
+#[allow(safe_extern_statics)]
 #[cfg(not(target_env = "msvc"))]
 mod globals {
     pub use h5i::hid_t as id_t;

libhdf5-sys/src/h5g.rs

@@ -42,6 +42,7 @@ impl Default for H5G_info_t {
     fn default() -> H5G_info_t { unsafe { ::std::mem::zeroed() } }
 }
 
+#[allow(safe_extern_statics)]
 extern {
     pub fn H5Gcreate2(loc_id: hid_t, name: *const c_char, lcpl_id: hid_t, gcpl_id: hid_t, gapl_id:
                       hid_t) -> hid_t;

libhdf5-sys/src/h5p.rs

@@ -154,6 +154,7 @@ mod globals {
     pub static H5P_LST_LINK_ACCESS: &'static id_t = &H5P_LST_LINK_ACCESS_g;
 }
 
+#[allow(safe_extern_statics)]
 #[cfg(all(hdf5_1_8_14, not(target_env = "msvc")))]
 mod globals {
     pub use h5i::hid_t as id_t;

libhdf5-sys/src/h5t.rs

@@ -301,6 +301,7 @@ extern {
 
 pub use self::globals::*;
 
+#[allow(safe_extern_statics)]
 #[cfg(not(target_env = "msvc"))]
 mod globals {
     pub use h5i::hid_t as id_t;