perf: Supply lower case prefix to "make install"

The man pages can't be found:

    buczek@geniux:~$ perf help stat
    No manual entry for perf-stat

The reason is, that the files get installed into "/" instread if "/usr",
because upper case PREFIX seems to be ignored by the build system. So
the man-pages where installed on the distmaster into /share/man, which
is invalid and is not disted to other nodes.

    [BEE] make -j 12 install PREFIX=/usr EPREFIX=/usr BINDIR=/usr/bin SBINDIR=/usr/sbin LIBEXECDIR=/usr/libexec SYSCONFDIR=/etc SHAREDSTATEDIR=/var LOCALSTATEDIR=/var LIBDIR=/usr/lib
INCLUDEDIR=/usr/include DATAROOTDIR=/usr/share DATADIR=/usr/share INFODIR=/usr/share/info LOCALEDIR=/usr/share/locale MANDIR=/usr/share/man DOCDIR=/usr/share/doc/perf DESTDIR=/scr
atch/local/bee-buczek/perf/perf-5.6.14-0/image
    [...]
    -rwxr-xr-x root/root   1034256 2020-05-20 09:38 /lib/libperf-gtk.so
    drwxr-xr-x root/root         0 2020-05-20 09:38 /lib/traceevent/
    drwxr-xr-x root/root         0 2020-05-20 09:38 /lib/traceevent/plugins/
    -rwxr-xr-x root/root     18032 2020-05-20 09:38 /lib/traceevent/plugins/plugin_jbd2.so
    -rwxr-xr-x root/root     20328 2020-05-20 09:38 /lib/traceevent/plugins/plugin_hrtimer.so
    [...]

Supply lower-cased prefixed argument as well, which seems to be honored:

    [BEE] make -j 12 install PREFIX=/usr EPREFIX=/usr BINDIR=/usr/bin SBINDIR=/usr/sbin LIBEXECDIR=/usr/libexec SYSCONFDIR=/etc SHAREDSTATEDIR=/var LOCALSTATEDIR=/var LIBDIR=/usr/lib
INCLUDEDIR=/usr/include DATAROOTDIR=/usr/share DATADIR=/usr/share INFODIR=/usr/share/info LOCALEDIR=/usr/share/locale MANDIR=/usr/share/man DOCDIR=/usr/share/doc/perf DESTDIR=/scr
atch/local/bee-buczek/perf/perf-5.6.14-0/image prefix=/usr
    [...]
    drwxr-xr-x root/root         0 2020-05-20 09:58 /usr/lib/traceevent/
    drwxr-xr-x root/root         0 2020-05-20 09:58 /usr/lib/traceevent/plugins/
    -rwxr-xr-x root/root     18032 2020-05-20 09:58 /usr/lib/traceevent/plugins/plugin_jbd2.so
    -rwxr-xr-x root/root     20328 2020-05-20 09:58 /usr/lib/traceevent/plugins/plugin_hrtimer.so
    [...]

Because PREFIX is now honored, remove $D$PREFIX/lib/perf/examples
instead of $D/lib/perf/examples.

perf.be0

@@ -34,11 +34,11 @@ mee_patch_post() {
 #    bee_build
 #}
 
-#mee_install() {
-#    bee_install
-#}
+mee_install() {
+    bee_install prefix=$PREFIX
+}
 
 mee_install_post() {
     rm -vrf ${D}/etc/bash_completion.d
-    rm -vrf ${D}/lib/perf/examples
+    rm -vrf ${D}${PREFIX}/lib/perf/examples
 }