Add Regex::CompileOptions::MULTILINE_ONLY

src/regex.cr

@@ -240,11 +240,15 @@ class Regex
     # flag that activates both behaviours, so here we do the same by
     # mapping `MULTILINE` to `PCRE_MULTILINE | PCRE_DOTALL`.
     # The same applies for PCRE2 except that the native values are 0x200 and 0x400.
+    # 
+    # For the behaviour of `PCRE_MULTILINE` use `MULTILINE_ONLY`.
 
     # Multiline matching.
     #
     # Equivalent to `MULTILINE | DOTALL` in PCRE and PCRE2.
     MULTILINE = 0x0000_0006
+    # Equivalent to `MULTILINE`in PCRE and PCRE2.
+    MULTILINE_ONLY = 0x0000_0040
 
     DOTALL = 0x0000_0002
 
@@ -600,6 +604,7 @@ class Regex
   # Regex.new("ab+c", :anchored).inspect # => Regex.new("ab+c", Regex::Options::ANCHORED)
   # ```
   def inspect(io : IO) : Nil
+    p! options, ~CompileOptions[IGNORE_CASE, MULTILINE, EXTENDED]
     if (options & ~CompileOptions[IGNORE_CASE, MULTILINE, EXTENDED]).none?
       inspect_literal(io)
     else

src/regex/pcre2.cr

@@ -68,6 +68,7 @@ module Regex::PCRE2
         flag |= case option
                 when .ignore_case?       then LibPCRE2::CASELESS
                 when .multiline?         then LibPCRE2::DOTALL | LibPCRE2::MULTILINE
+                when .multiline_only?    then LibPCRE2::MULTILINE
                 when .dotall?            then LibPCRE2::DOTALL
                 when .extended?          then LibPCRE2::EXTENDED
                 when .anchored?          then LibPCRE2::ANCHORED