pcre2: depends on zlib for Linuxbrew
pcre2: depends on zlib for Linuxbrew

An attempt to fix
```
** Cannot --enable-pcre2grep-libz because zlib.h was not found
```

Closes Linuxbrew/homebrew-core#2164.

Signed-off-by: Jonathan Chang <0bd51b8a224feeddb634965eebae512adcd49a8d@gmail.com>

maxim-belkin/homebrew-core,Linuxbrew/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,rwhogg/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,LinuxbrewTestBot/homebrew-core