esp8266: Allow building a board to any dest directory.

Signed-off-by: Damien George <damien@micropython.org>

ports/esp8266/boards/esp8266_common.ld

@@ -144,7 +144,7 @@ SECTIONS
         *shared/timeutils/*.o*(.literal*, .text*)
         *drivers/bus/*.o(.literal* .text*)
 
-        build-*/main.o(.literal* .text*)
+        */main.o(.literal* .text*)
         *fatfs_port.o(.literal* .text*)
         *gccollect.o(.literal* .text*)
         *gchelper.o(.literal* .text*)
@@ -182,7 +182,7 @@ SECTIONS
         */frozen.o(.rodata.mp_frozen_content) /* frozen modules */
 
         /* for -mforce-l32 */
-        build-*/*.o(.rodata*)
+        */*.o(.rodata*)
 
         _irom0_text_end = ABSOLUTE(.);
     } >irom0_0_seg :irom0_0_phdr