GLES/glext.h contains definition of functions:

glBindBufferOES(), glDeleteBuffersOES(), glGenBuffersOES(), glIsBufferOES(), glBufferDataOES(), glBufferSubDataOES(), 
glGetBufferParameterivOES().

And defines for GL_OES_vertex_buffer_object extension:

#define GL_ARRAY_BUFFER                                         0x8892
#define GL_ELEMENT_ARRAY_BUFFER                                 0x8893
.... etc.

This is incorrect, since all defines must have _OES suffix, since it is an extension, not a part of OpenGL ES 1.0. 
Defines must be like this:

#define GL_ARRAY_BUFFER_OES                                        0x8892
#define GL_ELEMENT_ARRAY_BUFFER_OES                          0x8893
.... etc.