pinebookpro-uboot: fix build w/ gcc10

Add -fcommon to CFLAGS for host and target.

srcpkgs/pinebookpro-uboot/files/fcommon-Makefile.patch

@@ -0,0 +1,20 @@
+--- pbp-uboot/Makefileg	2020-09-12 15:05:30.139856893 +0200
++++ pbp-uboot/Makefile	2020-09-12 15:06:45.963853869 +0200
+@@ -273,7 +273,7 @@
+ 
+ HOSTCC       = cc
+ HOSTCXX      = c++
+-HOSTCFLAGS   = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer \
++HOSTCFLAGS   = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fcommon \
+ 		$(if $(CONFIG_TOOLS_DEBUG),-g)
+ HOSTCXXFLAGS = -O2
+ 
+@@ -413,7 +413,7 @@
+ KBUILD_CPPFLAGS := -D__KERNEL__ -D__UBOOT__
+ 
+ KBUILD_CFLAGS   := -Wall -Wstrict-prototypes \
+-		   -Wno-format-security \
++		   -Wno-format-security -fcommon \
+ 		   -fno-builtin -ffreestanding $(CSTD_FLAG)
+ KBUILD_CFLAGS	+= -fshort-wchar -fno-strict-aliasing
+ KBUILD_AFLAGS   := -D__ASSEMBLY__

srcpkgs/pinebookpro-uboot/template

@@ -31,6 +31,7 @@ do_configure() {
 	unset CFLAGS CXXFLAGS CPPFLAGS LDFLAGS
 
 	cd pbp-uboot
+	patch -Np1 -i ${FILESDIR}/fcommon-Makefile.patch
 	make ${makejobs} pinebook_pro-rk3399_defconfig
 	echo 'CONFIG_IDENT_STRING=" Voidlinux"' >> .config
 }