Unbreak the build with -fno-common (Clang 11, GCC 10).

Reported by:	pkg-fallout

sysutils/read-edid/files/patch-get-edid_classic.c

@@ -14,6 +14,15 @@
  #include <unistd.h>
  
  #include <libx86.h>
+@@ -26,7 +26,7 @@ typedef byte* real_ptr;
+ #define dosmemput(buffer,length,offset) memcpy(offset,buffer,length)
+ 
+ #define display(...) if (quiet == 0) { fprintf(stderr, __VA_ARGS__); }
+-int quiet;
++extern int quiet;
+ 
+ real_ptr far_ptr_to_real_ptr( uint32 farptr )
+ {
 @@ -135,8 +135,17 @@ classicmain( unsigned contr, int qit )
        return 10;
      }

sysutils/read-edid/files/patch-get-edid_i2c.c

@@ -1,5 +1,14 @@
 --- get-edid/i2c.c.orig	2014-11-21 11:52:13 UTC
 +++ get-edid/i2c.c
+@@ -15,7 +15,7 @@
+ 
+ //Ideas (but not too much actual code) taken from i2c-tools. Thanks guys.
+ 
+-int quiet;
++extern int quiet;
+ 
+ #define display(...) if (quiet == 0) { fprintf(stderr, __VA_ARGS__); }
+ 
 @@ -24,7 +24,13 @@ int open_i2c_dev(int i2cbus) {
  	char filename[16];
  	unsigned long funcs;