adding support for almalinux (ref: #39)

[fabiocicerchia]

adding support for almalinux (ref: #39)

Added some extra guidelines in the DEV.md doc about how to add a new distro to the list

[fabiocicerchia]

Almalinux is configured automatically to use PCRE2, whilest Fedora doesn't. This is because the package pcre2-devel is installed, and required by openssl-devel.

[...]

checking for PCRE2 library ... found
checking for OpenSSL library ... found
checking for zlib library ... found
creating objs/Makefile

Configuration summary
  + using threads
  + using system PCRE2 library
  + using system OpenSSL library
  + using system zlib library

  nginx path prefix: "/etc/nginx"
  nginx binary file: "/usr/sbin/nginx"
  nginx modules path: "/usr/lib/nginx/modules"
  nginx configuration prefix: "/etc/nginx"

[...]

While configuring nginx the default value for PCRE2 is YES.
So it takes the precedence over PCRE, in fact it uses the flag -lpcre2.8:

[...]
-L/usr/local/lib -L/usr/local/lib -Wl,-rpath,/usr/local/lib -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie -lpcre -Wl,--require-defined=pcre_version -Wl,-E -Wl,-E -ldl -lpthread -lpthread -lcrypt -L/usr/local/lib -lluajit-5.1 -lm -ldl -L/usr/local/lib -lluajit-5.1 -lm -ldl -lpcre2-8 -lssl -lcrypto -ldl -lpthread -lz \
-Wl,-E
[...]

The solution would be to link as well the PCRE library in order to resolve correctly the missing symbols:

• use the flag -lpcre in LDOPT
• use the flag --without-pcre2 in the nginx configure