Port over vezel/libffi zig package

[Techatrix]

This PR ports over https://codeberg.org/vezel/libffi which is also packages libffi for Zig. It has been maintained by alexrp, a ZSF core team member which as has extensive knowledge in compilation target support. Unfortunately, this fork is no longer maintained so I'm hoping to revive it in the allyourcodebase organization.

I have tested this port with https://github.com/allyourcodebase/tracy which depends on https://github.com/allyourcodebase/wayland and therefore libffi.

[Techatrix]

@Tomcat-42

[Tomcat-42]

Hi @Techatrix, thanks for the patch. One thing, I will merge this and point a 0.16 branch to HEAD, and then commit:

diff --git a/build.zig b/build.zig
index e393ccd..ce29cb4 100644
--- a/build.zig
+++ b/build.zig
@@ -209,8 +209,8 @@ pub fn build(b: *std.Build) !void {
     inline for (.{ "include", "src", b.pathJoin(&.{ "src", arch_name }) }) |inc|
         mod.addIncludePath(upstream.path(inc));
 
-    const double_size = t.cTypeByteSize(.double);
-    const long_double_size = t.cTypeByteSize(.longdouble);
+    const double_size = t.cTypeByteSize(.double).?;
+    const long_double_size = t.cTypeByteSize(.longdouble).?;
 
     const long_double_variant = switch (t.os.tag) {
         .freebsd, .netbsd, .openbsd => t.cpu.arch == .powerpc,

on top. It is ok for you? I was long wanting to separate the master and 0.xx branch for bindings repos like this.

[Tomcat-42]

Also thanks for the patch, this repo was in need of a little housekeeping

[Techatrix]

You can also keep a single branch and check whether cTypeByteSize will need to be unwrapped at comptime:

diff --git a/build.zig b/build.zig
index e393ccd..b101896 100644
--- a/build.zig
+++ b/build.zig
@@ -209,8 +209,11 @@ pub fn build(b: *std.Build) !void {
     inline for (.{ "include", "src", b.pathJoin(&.{ "src", arch_name }) }) |inc|
         mod.addIncludePath(upstream.path(inc));
 
-    const double_size = t.cTypeByteSize(.double);
-    const long_double_size = t.cTypeByteSize(.longdouble);
+    // the `is_c_byte_size_optional` check can be removed when targetting 0.17.0+
+    comptime std.debug.assert((std.SemanticVersion.parse(manifest.minimum_zig_version) catch unreachable).minor < 17);
+    const is_c_byte_size_optional = @typeInfo(@typeInfo(@TypeOf(std.Target.cTypeBitSize)).@"fn".return_type.?) == .optional;
+    const double_size = if (is_c_byte_size_optional) t.cTypeByteSize(.double).? else t.cTypeByteSize(.double);
+    const long_double_size = if (is_c_byte_size_optional) t.cTypeByteSize(.longdouble).? else t.cTypeByteSize(.longdouble);
 
     const long_double_variant = switch (t.os.tag) {
         .freebsd, .netbsd, .openbsd => t.cpu.arch == .powerpc,