Require rust >= 1.25 and drop libc_align conditional

This is mostly taken from Josh's work at [1], I just updated to account
for conflicts and new uses of `libc_align`.

[1]: rust-lang#2845

Co-authored-by: Josh Triplett <josh@joshtriplett.org>

(apply <rust-lang#4057> to `main`)
(cherry picked from commit b5b553d)

As part of this update, drop the `align` feature from Cargo.toml and
libc-test.

Author: tgross35

Cargo.toml

@@ -139,8 +139,7 @@ rustc-std-workspace-core = { version = "1.0.0", optional = true }
 [features]
 default = ["std"]
 std = []
-align = []
-rustc-dep-of-std = ['align', 'rustc-std-workspace-core']
+rustc-dep-of-std = ["rustc-std-workspace-core"]
 extra_traits = []
 const-extern-fn = []
 

libc-test/Cargo.toml

@@ -24,7 +24,6 @@ ctest2 = "0.4.3"
 [features]
 default = ["std"]
 std = ["libc/std"]
-align = ["libc/align"]
 extra_traits = ["libc/extra_traits"]
 
 [[test]]