2.37 tarballs have empty manual pages

[Matthias Klose]

something got wrong when generating the 2.37 tarballs, all manual pages are
included, but have a size of 0 bytes.

./binutils/doc/nm.1
./binutils/doc/dlltool.1
./binutils/doc/elfedit.1
./binutils/doc/windmc.1
./binutils/doc/windres.1
./binutils/doc/strip.1
./binutils/doc/objcopy.1
./binutils/doc/objdump.1
./binutils/doc/strings.1
./binutils/doc/readelf.1
./binutils/doc/addr2line.1
./binutils/doc/ranlib.1
./binutils/doc/ar.1
./binutils/doc/c++filt.1
./binutils/doc/size.1
./gas/doc/as.1
./ld/ld.1
./gprof/gprof.1

$ tar tvf binutils-2.37.tar.xz |grep strings.1
-rw-rw-rw- nickc/nickc       0 2021-07-18 18:48 binutils-2.37/binutils/doc/strings.1
-rwxrwxrwx nickc/nickc      31 2021-07-08 13:37
binutils-2.37/binutils/testsuite/binutils-all/strings-1.bin

A work around to properly build these pages is to remove these empty files
before starting a build.

Maybe add a check in the build scripts that these pages are preoperly included
in the tarballs?

Thanks, Matthias