pxe_api.h: finish revert of 9acbffd

9acbffd caused more issues than it solves.
There appears to be a bigger underlying issue that the __weak argument masks.
Until the underlying issue is solved, we need __weak.

Signed-off-by: Gene Cumm <gene.cumm@gmail.com>

com32/include/syslinux/pxe_api.h

@@ -587,9 +587,9 @@ typedef struct s_PXENV_UNLOAD_STACK {
 
 int __weak pxe_call(int, void *);
 void __weak unload_pxe(uint16_t flags);
-uint32_t pxe_dns(const char *);
+uint32_t __weak pxe_dns(const char *);
 
-extern uint32_t SendCookies;
-void http_bake_cookies(void);
+extern uint32_t __weak SendCookies;
+void __weak http_bake_cookies(void);
 
 #endif /* _SYSLINUX_PXE_API_H */