add more inlines for better optimization

[camshaft]

in trying to improve iteration speeds i noticed the panic functions showing up a bit. after making these changes, iteration speed has improved slightly:

boolean-tree example

$ cd examples/boolean-tree
$ cargo +nightly bolero test tests::model_test --engine random --sanitizer NONE

before

#3929088	iterations/s: 3929088
#7855104	iterations/s: 3926016
#11784192	iterations/s: 3929088
#15715328	iterations/s: 3931136
#19649536	iterations/s: 3934208
#23584768	iterations/s: 3935232

after

#4470784	iterations/s: 4470784
#8924160	iterations/s: 4453376
#13398016	iterations/s: 4473856
#17874944	iterations/s: 4476928
#22356992	iterations/s: 4482048
#26848256	iterations/s: 4491264