main/linux-postmarketos-qcom-msm8974: add findutils build dependency (!1090)

Forces to use normal "find" instead of busybox find.
This fixes unrecognized -printf parameter error dutring build:

 ...
 GEN     usr/initramfs_data.cpio
find: unrecognized: -printf
BusyBox v1.31.1 () multi-call binary.

Usage: find [-HL] [PATH]... [OPTIONS] [ACTIONS]
 ...

main/linux-postmarketos-qcom-msm8974/APKBUILD

@@ -4,12 +4,12 @@ _config="config-$_flavor.$CARCH"
 pkgname=linux-$_flavor
 
 pkgver=5.6.0_rc6
-pkgrel=0
+pkgrel=1
 
 arch="armv7"
 pkgdesc="Kernel close to mainline with extra patches for Qualcomm MSM8974 devices"
 url="https://kernel.org/"
-makedepends="dtbtool perl sed installkernel bash gmp-dev bc linux-headers elfutils-dev openssl-dev file bison flex"
+makedepends="dtbtool perl sed installkernel bash gmp-dev bc linux-headers elfutils-dev openssl-dev file bison flex findutils"
 options="!strip !check !tracedeps"
 _commit="5e47680b0bbc71dbc093123790951cc81eb2b84e"
 source="