Add @nogc UDA, fix some small issues, xmake changes

-add @nogc to some functions where it was missing
-fix compilation issue in mallocator
-fix Meson build
-some work on xmake build

xmake.lua

@@ -1,15 +1,25 @@
 add_rules("mode.debug", "mode.release")
 
+if get_config("toolchain") == "ldc" then
+    add_ldflags("-linker=lld", {force = true})
+end
+
 option("betterC")
     set_default(false)
-    if get_config("dc") == "gcc" then
+    if get_config("toolchain") == "gdc" then
         add_dcflags("-fno-druntime")
+    elseif get_config("toolchain") == "dmd" then
+        add_dcflags("-betterC") -- DMD doesn't need -betterC flag during linking!?
+        add_ldflags("-betterC", {force = true})
+        add_shflags("-betterC", {force = true})
     else
-        add_dcflags("-betterC")
+        add_ldflags("-betterC", {force = true}) -- -betterC flag isn't accepted for LDC for some reason
+        add_dcflags("-betterC", {force = true})
+        add_shflags("-betterC", {force = true})
     end 
 
 target("bubel-ecs")
-    set_kind("static")
+    set_kind("shared")
     set_basename("BubelECS")
     add_files("source/bubel/**.d")
     add_includedirs("source", {public = true})
@@ -18,6 +28,7 @@ target("bubel-ecs")
 target("tests")
     set_kind("binary")
     set_basename("BubelECSTests")
+    add_ldflags("-L-rpath=.", {force = true})
     add_files("tests/*.d|tests.d")
     add_includedirs(".", {public = true})
     set_options("betterC")
@@ -27,6 +38,8 @@ target("tests")
 target("test")
     set_kind("binary")
     set_basename("BubelECSTest")
+    -- add_rpathdirs(".") -- this doesn't work completely
+    add_ldflags("-L-rpath=.", {force = true})
     add_files("tests/tests.d")
     add_includedirs(".", {public = true})
     set_options("betterC")