[bug-gnu-libiconv] Compiler warnings regarding casting pointer to `long` on some platforms

[Nathan Du]

Hello.

When compiling libiconv on x86_64-w64-

mingw32, GCC raises compiler warnings that

does not occur on x86_64-*-linux-gnu. This

bug is not found by me, but by someone else

working on MSYS2, a project aiming to provide

a Unix-like development environment on W32.

The offending files are automatically generated

using `genaliases.c` and `genaliases2.c`. The

lines resulting in compiler warnings are written

at

[line 53](https://git.savannah.gnu.org/gitweb/?p=libiconv.git;a=blob;f=lib/genaliases.c;h=de7d705cde16360570db07f9a285bd4bac708e2d;hb=HEAD#l53)

of `genaliases.c`, and

[line 46](https://git.savannah.gnu.org/gitweb/?p=libiconv.git;a=blob;f=lib/genaliases2.c;h=51a951cc87c0d2c95e446b93734e766aa04abd95;hb=HEAD#l46)

of `genalaiases2.c`.

The code assumes that sizeof(long) is equal to

sizeof(void *). This however does not always

hold true. A notable example is W32 running

on AMD64, where sizeof(long) equals

sizeof(int32_t), which isn’t equal to the size of

`void *`.

For portability, we may need to cast to a type

other than `long`. gperf generated code, for

example, casts to `size_t`, and we should

probably follow suit. Other sensible choices

include casting to `intptr_t`.

Nathan Du