patch 8.1.1384: using "int" for alloc() often results in compiler warnings

Problem:    Using "int" for alloc() often results in compiler warnings.
Solution:   Use "size_t" and remove type casts.  Remove alloc_check(), Vim
            only works with 32 bit ints anyway.
diff --git a/src/proto/misc2.pro b/src/proto/misc2.pro
index 566c973..687cfed 100644
--- a/src/proto/misc2.pro
+++ b/src/proto/misc2.pro
@@ -20,21 +20,20 @@
 void adjust_cursor_col(void);
 int leftcol_changed(void);
 void vim_mem_profile_dump(void);
-int alloc_does_fail(long_u size);
-char_u *alloc(unsigned size);
-char_u *alloc_id(unsigned size, alloc_id_T id);
-char_u *alloc_clear(unsigned size);
-char_u *alloc_clear_id(unsigned size, alloc_id_T id);
-char_u *alloc_check(unsigned size);
-char_u *lalloc_clear(long_u size, int message);
-char_u *lalloc(long_u size, int message);
-char_u *lalloc_id(long_u size, int message, alloc_id_T id);
+int alloc_does_fail(size_t size);
+char_u *alloc(size_t size);
+char_u *alloc_id(size_t size, alloc_id_T id);
+char_u *alloc_clear(size_t size);
+char_u *alloc_clear_id(size_t size, alloc_id_T id);
+char_u *lalloc_clear(size_t size, int message);
+char_u *lalloc(size_t size, int message);
+char_u *lalloc_id(size_t size, int message, alloc_id_T id);
 void *mem_realloc(void *ptr, size_t size);
-void do_outofmem_msg(long_u size);
+void do_outofmem_msg(size_t size);
 void free_all_mem(void);
 char_u *vim_strsave(char_u *string);
 char_u *vim_strnsave(char_u *string, int len);
-char_u *vim_memsave(char_u *p, int len);
+char_u *vim_memsave(char_u *p, size_t len);
 char_u *vim_strsave_escaped(char_u *string, char_u *esc_chars);
 char_u *vim_strsave_escaped_ext(char_u *string, char_u *esc_chars, int cc, int bsl);
 int csh_like_shell(void);