`which` utility is not shipped by default for example on recent Arch
Linux and then any steps relying on its presence fails, like for example
following Python3 prereq build check:
$ python3 --version
Python 3.9.1
$ make
/bin/sh: line 1: which: command not found
...
Checking 'python3'... failed.
So make `which` utility host build requirement.
References: PR#3820 FS#3525
Signed-off-by: Petr Štetiar <ynezz@true.cz>
```
gcc-6+ binutils bzip2 flex python3 perl make4.1+ find grep diff unzip gawk getopt
-subversion libz-dev libc-dev rsync
+subversion libz-dev libc-dev rsync which
```
### Quickstart
$(eval $(call SetupHostCommand,rsync,Please install 'rsync', \
rsync --version </dev/null))
+$(eval $(call SetupHostCommand,which,Please install 'which', \
+ which which | grep which))
+
$(STAGING_DIR_HOST)/bin/mkhash: $(SCRIPT_DIR)/mkhash.c
mkdir -p $(dir $@)
$(CC) -O2 -I$(TOPDIR)/tools/include -o $@ $<