Remove `SmallVec` in favor of using a long-term `Vec`

[Jon Gjengset]

See #78 (comment). Specifically, currently we use a SmallVec for temporarily holding inlined java method calls:

inferno/src/collapse/perf.rs

Lines 278 to 279 in 10a1fd7

 let mut java_inline = 
     SmallVec::<[String; 1]>::with_capacity(rawfunc.split("->").count() + 1); 

However, in #78, @Licenser decided to instead re-use a Vec in the Folder, which seems like a better strategy since it generally won't allocate even if there are inlined method calls (unlike SmallVec, which will allocate every time that happens).