Cygwin, gfortran and C interop

[Anthony Stone <ajs1 at cam dot ac dot uk>]

I am trying to link a program that uses the C interoperability features 
of Fortran 2003 to call OpenGL routines. This works fine under Linux, 
but not under Cygwin. The problem is that the linker is looking for 
(e.g.) '_glBegin':
gl_module.o:gl_module.F90:(.text+0x293c): undefined reference to `_glBegin'
but the OpenGL library in /lib/w32api/libopengl32.a provides '_glBegin@4':
 $ nm 'c:\cygwin\lib\w32api\libopengl32.a' | grep glBegin
00000000 I __imp__glBegin@4
00000000 T _glBegin@4

The Fortran code contains the following interface:
INTERFACE
SUBROUTINE glBegin(mode) BIND(C,NAME="glBegin")
IMPORT
INTEGER(GLenum), VALUE :: mode
END SUBROUTINE glBegin
END INTERFACE

Can I modify the interface to persuade gfortran to generate the right 
reference? The Nag compiler provides the possibility of modifying the 
interface to
INTERFACE
SUBROUTINE glBegin(mode) BIND(C,NAME="__stdcall glBegin")
IMPORT
INTEGER(GLenum), VALUE :: mode
END SUBROUTINE glBegin
END INTERFACE
and then it generates a reference to _glBegin@4 as required.

gfortran doesn't accept this, but does it provide some other way round 
the problem?

Anthony Stone