perlcross: check the file if patched or not

After the commit(60dcb230 perl: split perl-cross into its own recipe)
introduced, the source files mainly come from two parts, one is from
SRI_URI during do_fetch and the other with below means during do_configure.
do_configure_prepend() {
    cp -rfp ${STAGING_DATADIR_NATIVE}/perl-cross/* ${S}
}

And the source files will be changed during do_compile with below
logic in Makefile.
$(CROSSPATCHED): %.applied: %.patch
        patch -p1 -i $< && touch $@

And there comes build failure with below steps:
 $ bitbake perl-native

Make a change as below
 $ git diff
 diff --git a/meta/recipes-devtools/perl-cross/perlcross_1.3.6.bb b/meta/recipes-devtools/perl-cross/perlcross_1.3.6.bb
 index b77bbd1fd4..4c5e35ab80 100644
 --- a/meta/recipes-devtools/perl-cross/perlcross_1.3.6.bb
 +++ b/meta/recipes-devtools/perl-cross/perlcross_1.3.6.bb
 @@ -33,6 +33,7 @@ do_compile () {
  do_install_class-native() {
      mkdir -p ${D}/${datadir}/perl-cross/
      cp -rf ${S}/* ${D}/${datadir}/perl-cross/
 +    echo "test" > ${D}/${datadir}/perl-cross/testfile
 }

 $ bitbake perl-native
 | NOTE: make -j 48
 | make crosspatch
 | make[1]: Entering directory '/buildarea1/myu2/wr_build/wr1021_20210616_perl/build/tmp-glibc/work/x86_64-linux/perl-native/5.34.0-r0/perl-5.34.0'
 | patch -p1 -i cnf/diffs/perl5-5.34.0/time-hires.patch && touch cnf/diffs/perl5-5.34.0/time-hires.applied
 | patch -p1 -i cnf/diffs/perl5-5.34.0/xconfig.patch && touch cnf/diffs/perl5-5.34.0/xconfig.applied
 | patch -p1 -i cnf/diffs/perl5-5.34.0/posix-makefile.patch && touch cnf/diffs/perl5-5.34.0/posix-makefile.applied
 | File dist/Time-HiRes/Makefile.PL is read-only; trying to patch anyway
 | patching file dist/Time-HiRes/Makefile.PL
 | Reversed (or previously applied) patch detected!  Assume -R? [n]
 | Apply anyway? [n]
 | Skipping patch.
 | 4 out of 4 hunks ignored -- saving rejects to file dist/Time-HiRes/Makefile.PL.rej
 | patch -p1 -i cnf/diffs/perl5-5.34.0/test-commonsense.patch && touch cnf/diffs/perl5-5.34.0/test-commonsense.applied
 | File perl.h is read-only; trying to patch anyway
 | patching file perl.h
 | Reversed (or previously applied) patch detected!  Assume -R? [n]
 | Apply anyway? [n]
 | Skipping patch.
 | 1 out of 1 hunk ignored -- saving rejects to file perl.h.rej
 | make[1]: *** [Makefile:64: cnf/diffs/perl5-5.34.0/time-hires.applied] Error 1
 [snip]

It's because the source files patched twice, so check the file if patched
or not to avoid the source files patched more than one time to fix the
build failure as above.

Signed-off-by: Mingli Yu <mingli.yu@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>