Fix #27360's unused import
Fix #27360's unused import

#27360 removed a padding field full of uint8_t's, but didn't remove
the use.  This didn't get picked up presumably because (a) bors
doesn't have any BSD builders, and/or (b) #[cfg]'d out blocks don't
get linted.

```
rustc: x86_64-unknown-freebsd/stage1/lib/rustlib/x86_64-unknown-freebsd/lib/liblibc
src/liblibc/lib.rs:1099:42: 1099:49 error: unused import, #[deny(unused_imports)] on by default
src/liblibc/lib.rs:1099                 use types::common::c99::{uint8_t, uint32_t, int32_t};
                                                                 ^~~~~~~
error: aborting due to previous error
fatal runtime error: Could not unwind stack, error = 159555904
```
jroesch/rust,vhbit/rust,GBGamer/rust,dwillmer/rust,jroesch/rust,vhbit/rust,jroesch/rust,GBGamer/rust,dwillmer/rust,graydon/rust,dwillmer/rust,jroesch/rust,aidancully/rust,jashank/rust,dwillmer/rust,graydon/rust,zubron/rust,zubron/rust,jroesch/rust,jashank/rust,zubron/rust,zubron/rust,zubron/rust,dwillmer/rust,aidancully/rust,jashank/rust,GBGamer/rust,jroesch/rust,vhbit/rust,aidancully/rust,aidancully/rust,l0kod/rust,GBGamer/rust,aidancully/rust,l0kod/rust,jashank/rust,pshc/rust,GBGamer/rust,l0kod/rust,pshc/rust,vhbit/rust,pshc/rust,l0kod/rust,zubron/rust,vhbit/rust,l0kod/rust,pshc/rust,jashank/rust,pshc/rust,jashank/rust,vhbit/rust,dwillmer/rust,dwillmer/rust,jashank/rust,pshc/rust,GBGamer/rust,graydon/rust,jroesch/rust,jroesch/rust,l0kod/rust,GBGamer/rust,jashank/rust,graydon/rust,vhbit/rust,aidancully/rust,dwillmer/rust,vhbit/rust,l0kod/rust,graydon/rust,pshc/rust,GBGamer/rust,graydon/rust,zubron/rust,l0kod/rust,pshc/rust,zubron/rust