fixes & cleanups

- tccgen.c/tcc.h: allow function declaration after use:
      int f() { return g(); }
      int g() { return 1; }
  may be a warning but not an error
  see also 76cb1144ef

- tccgen.c: redundant code related to inline functions removed
  (functions used anywhere have sym->c set automatically)

- tccgen.c: make 32bit llop non-equal test portable
  (probably not on C67)

- dynarray_add: change prototype to possibly avoid aliasing
  problems or at least warnings

- lib/alloca*.S: ".section .note.GNU-stack,"",%progbits" removed
  (has no effect)

- tccpe: set SizeOfCode field (for correct upx decompression)

- libtcc.c: fixed alternative -run invocation
      tcc "-run -lxxx ..." file.c
  (meant to load the library after file).
  Also supported now:
      tcc files ... options ... -run @ arguments ...

lib/alloca-arm.S

@@ -8,4 +8,3 @@ alloca:
 	mov	r0, sp
 	mov	pc, lr
 	.size	alloca, .-alloca
-	.section	.note.GNU-stack,"",%progbits

lib/alloca86.S

@@ -28,8 +28,4 @@ p3:
     push    %edx
     ret
 
-/* mark stack as nonexecutable */
-#if defined __ELF__ && defined __linux__
-    .section    .note.GNU-stack,"",@progbits
-#endif
 /* ---------------------------------------------- */

lib/alloca86_64-bt.S

@@ -53,8 +53,4 @@ p3:
     ret
 #endif
 
-/* mark stack as nonexecutable */
-#if defined __ELF__ && defined __linux__
-    .section    .note.GNU-stack,"",@progbits
-#endif
 /* ---------------------------------------------- */

lib/alloca86_64.S

@@ -35,8 +35,4 @@ p3:
     push    %rdx
     ret
 
-/* mark stack as nonexecutable */
-#if defined __ELF__ && defined __linux__
-    .section    .note.GNU-stack,"",@progbits
-#endif
 /* ---------------------------------------------- */