Update .gitignore (#14158)

- The headers mentioned in the comment are not "generated" anymore as
  done via eb76a83
- zend_jit_<arch>.c files are now generated as part of the
  ext/opcache/jit/ir
- generated minilua is ignored in ext/opcache/jit/ir/.gitignore

Author: petk

.gitignore

@@ -78,7 +78,7 @@ Makefile
 Makefile.fragments
 Makefile.objects
 
-# Directories for shared object files and headers generated by `./configure`
+# Directories for shared object files generated by `./configure`
 libs/
 modules/
 
@@ -166,11 +166,6 @@ php
 # Extensions files
 # ------------------------------------------------------------------------------
 
-# Miscellaneous extensions files
-/ext/opcache/jit/zend_jit_x86.c
-/ext/opcache/jit/zend_jit_arm64.c
-/ext/opcache/minilua
-
 # Generated by `cd ext/name && phpize && ./configure`
 /ext/*/build/
 /ext/*/configure.ac