Rollup merge of rust-lang#70708 - Pocakking:fix-ascii-case-conv-typo,…

… r=sfackler

Fix typo in u8::to_ascii_uppercase and u8::to_ascii_lowercase

Corrects misspelling of fifth.

src/libcore/num/mod.rs

@@ -4376,7 +4376,7 @@ impl u8 {
  #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
  #[inline]
  pub fn to_ascii_uppercase(&self) -> u8 {
- // Unset the fith bit if this is a lowercase letter
+ // Unset the fifth bit if this is a lowercase letter
  *self & !((self.is_ascii_lowercase() as u8) << 5)
  }
 
@@ -4399,7 +4399,7 @@ impl u8 {
  #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
  #[inline]
  pub fn to_ascii_lowercase(&self) -> u8 {
- // Set the fith bit if this is an uppercase letter
+ // Set the fifth bit if this is an uppercase letter
  *self | ((self.is_ascii_uppercase() as u8) << 5)
  }