Remove redundant case_Lisp_Int macro

Remove redundant case_Lisp_Int macro

The case_Lisp_Int macro was originally introduced with different
definitions depending on USE_2_TAGS_FOR_INTS.  However, since commit
2b5701247845, we have assumed that USE_2_TAGS_FOR_INTS is always
defined, and the macro has only a single definition.  As a result, the
macro is now unnecessary, and replacing it with standard C case labels
improves readability and understanding.

* src/lisp.h (case_Lisp_Int): Delete macro.
* src/alloc.c (process_mark_stack, survives_gc_p):
* src/data.c (Fcl_type_of):
* src/fns.c (value_cmp, sxhash_obj):
* src/pdumper.c (dump_object):
* src/print.c (print_object):
* src/xfaces.c (face_attr_equal_p): Remove uses of above macro.

(cherry picked from commit 278d1994af4c52a5590c793d27d8fd2867fe7a66)