Ensure crate is compiled with std for panic handler

This CL adds a patch to use `extern crate std` to ensure that a panic
handler is available when the crate is compiled as a dylib.

Test: m libryu
Bug: 333887339
Change-Id: I6ef6b9d84e8a3440825b3f271c06378bf5eaf022
diff --git a/patches/std.diff b/patches/std.diff
new file mode 100644
index 0000000..93ef036
--- /dev/null
+++ b/patches/std.diff
@@ -0,0 +1,14 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index cf3a732..83f6bdf 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -116,6 +116,9 @@ mod f2s;
+ mod f2s_intrinsics;
+ mod pretty;
+ 
++#[cfg(android_dylib)]
++extern crate std;
++
+ pub use crate::buffer::{Buffer, Float};
+ 
+ /// Unsafe functions that mirror the API of the C implementation of Ryū.
diff --git a/src/lib.rs b/src/lib.rs
index cf3a732..83f6bdf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -116,6 +116,9 @@
 mod f2s_intrinsics;
 mod pretty;
 
+#[cfg(android_dylib)]
+extern crate std;
+
 pub use crate::buffer::{Buffer, Float};
 
 /// Unsafe functions that mirror the API of the C implementation of Ryū.