dante: Add -P to preprocessor flags

configure uses AC_PREPROC_IFELSE to check for certain errors from getaddrinfo()
it user search operation in a preprocessed file

 UNIQUEVALS=`sort $ERRVALFILE | uniq | wc -l | awk '{ print $1 }'`

However, line numbers are generated into the preprocesser files and they
get sorted higher than numbers

 gaierrval:
 # 130 "conftest.c" 3 4
           -3

-P ensures that line numbers are not generated into preprocessed files,
so these checks can succeed.

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-networking/recipes-protocols/dante/dante_1.4.3.bb

@@ -25,6 +25,7 @@ EXTRA_OECONF += "--without-gssapi --sbindir=${bindir}"
 DEPENDS += "flex-native bison-native libpam libtirpc"
 inherit autotools-brokensep features_check
 
+CPPFLAGS += "-P"
 CFLAGS += "-I${STAGING_INCDIR}/tirpc"
 LIBS += "-ltirpc"