GTK4: Move a few more functions into thread safety. Add API to functions that were missing it. API is used for speficying calling convention, that isn't usually required on Unix, but should be there for future use. The thread safety macros will automatically add API, so just required to add it to ones not in the thread safety system.

prefix=@prefix@
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${exec_prefix}/include
 
Name: dwindows
Description: Dynamic Windows Cross platform UI Toolkit
Version: @VERSION@
Libs: -L${prefix}/lib -ldwindows @LIBS@
Cflags: -I${prefix}/include @CFLAGS@ -D@DW_DEFINE@