partial revert 9acbffd

Weaken 2 declarations.  Seems to be the minimal amount for now.

First exhibited issues with EFI but later also with BIOS beyond *pxelinux.0
when compiled with gcc-5.3.1 and gcc-6.

Signed-off-by: Gene Cumm <gene.cumm@gmail.com>
diff --git a/com32/include/syslinux/pxe_api.h b/com32/include/syslinux/pxe_api.h
index 40794e7..9b90e63 100644
--- a/com32/include/syslinux/pxe_api.h
+++ b/com32/include/syslinux/pxe_api.h
@@ -585,8 +585,8 @@
 #define PXENV_STATUS_LOADER_UNDI_START			 0xca
 #define PXENV_STATUS_LOADER_BC_START			 0xcb
 
-int pxe_call(int, void *);
-void unload_pxe(uint16_t flags);
+int __weak pxe_call(int, void *);
+void __weak unload_pxe(uint16_t flags);
 uint32_t pxe_dns(const char *);
 
 extern uint32_t SendCookies;