basicauth: Minor internal improvements (#3861)

* nitpicks and small improvements in basicauth module

1:
roll two if statements into one, since err will be nil in the second case anyhow

2:
unlock cache mutex after reading the key, as this happens by-value and reduces code complexity

3:
switch cache sync.Mutex to sync.RWMutex for better concurrency on cache fast track

* allocate the right kind of mutex

0 files changed, 0 insertions, 0 deletions