Fixes for compiling with -fno-common, default in GCC 10.

Taken from upstream:
https://github.com/qca/open-ath9k-htc-firmware/commit/559e3eba3b4cf103da6b8d022f3e1387278b9db8

diff --git a/target_firmware/magpie_fw_dev/target/init/app_start.c b/target_firmware/magpie_fw_dev/target/init/app_start.c
--- a/target_firmware/magpie_fw_dev/target/init/app_start.c
+++ b/target_firmware/magpie_fw_dev/target/init/app_start.c
@@ -52,6 +52,8 @@
 #define ALLOCRAM_START       ( ((unsigned int)&_fw_image_end) + 4)
 #define ALLOCRAM_SIZE        ( SYS_RAM_SZIE - ( ALLOCRAM_START - SYS_D_RAM_REGION_0_BASE) - SYS_D_RAM_STACK_SIZE)
 
+void (* _assfail_ori)(struct register_dump_s *);
+
 // support for more than 64 bytes on command pipe
 extern void usb_reg_out_patch(void);
 extern int _HIFusb_get_max_msg_len_patch(hif_handle_t handle, int pipe);
diff --git a/target_firmware/magpie_fw_dev/target/init/init.h b/target_firmware/magpie_fw_dev/target/init/init.h
--- a/target_firmware/magpie_fw_dev/target/init/init.h
+++ b/target_firmware/magpie_fw_dev/target/init/init.h
@@ -46,7 +46,7 @@
 void AR6002_fatal_exception_handler_patch(CPU_exception_frame_t *exc_frame);
 void exception_reset(struct register_dump_s *dump);
 
-void (* _assfail_ori)(struct register_dump_s *);
+extern void (* _assfail_ori)(struct register_dump_s *);
 void HTCMsgRecvHandler_patch(adf_nbuf_t hdr_buf, adf_nbuf_t buffer, void *context);
 void HTCControlSvcProcessMsg_patch(HTC_ENDPOINT_ID EndpointID, adf_nbuf_t hdr_buf,
 				   adf_nbuf_t pBuffers, void *arg);
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<div class='path'>path: <a href='/guix/log/?id=582b1f626f351d0c519c973ba3c49d1c270200bf'>root</a>/<a href='/guix/log/gnu?id=582b1f626f351d0c519c973ba3c49d1c270200bf'>gnu</a>/<a href='/guix/log/gnu/services?id=582b1f626f351d0c519c973ba3c49d1c270200bf'>services</a>/<a href='/guix/log/gnu/services/audio.scm?id=582b1f626f351d0c519c973ba3c49d1c270200bf'>audio.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/services/audio.scm?id=582b1f626f351d0c519c973ba3c49d1c270200bf&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-06 23:18:08 +0100'>2020-12-06</span></td><td><a href='/guix/commit/gnu/services/audio.scm?id=ce3b5e5a8d8566162201cb778c4586f94a626dfa'>services: mpd: Make /var/run/mpd/USER user-owned.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/44820&gt;.
Reported by Simon &lt;lists@netpanic.org&gt;.

This is a followup to bb124f6e9c0af0a23736f233c2ea2c9c9b4a40a6.

* gnu/services/audio.scm (mpd-service-activation): Chown the parent of
DIRECTORY as well.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-06 23:10:18 +0100'>2020-11-06</span></td><td><a href='/guix/commit/gnu/services/audio.scm?id=bb124f6e9c0af0a23736f233c2ea2c9c9b4a40a6'>services: mpd: Fix daemon startup.</a><span class='msg-avail'>...<span class='msg-tooltip'>Until now it would wait for a PID file that'd never come.

* gnu/services/audio.scm (mpd-shepherd-service): Add 'requirement'.
Remove #:pid-file from 'start'.
(mpd-service-activation): Create the ".mpd" directory since that's what
the daemon expects.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-06 22:59:19 +0100'>2020-11-06</span></td><td><a href='/guix/commit/gnu/services/audio.scm?id=7209d7cbc37c108ca1148561a681258bb2222ab1'>services: mpd: Always create the "mpd" user account.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/audio.scm (%mpd-accounts): New variable.
(mpd-service-type)[extensions]: Add ACCOUNT-SERVICE-TYPE extension.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-06 08:54:27 -0500'>2020-11-06</span></td><td><a href='/guix/commit/gnu/services/audio.scm?id=0c5d0c57d370b34f3ba677838deaa8baf7bca58a'>services: mpd: Do not eagerly look for a user.</a><span class='msg-avail'>...<span class='msg-tooltip'>Running 'guix system search mpd' would throw a backtrace because the
mpd-shepherd-service service start Gexp contained an unquoted call to
'getpwnam', which would look for a missing 'mpd' user and fail.

* gnu/services/audio.scm (mpd-shepherd-service): gexp-unquote only the
relevant variable rather than the whole expression.
</span></span></td><td>Maxim Cournoyer</td></tr>