Patch is taken from ncurses upstream repository.

The problem it solves is that gcc 5.1 and later adds spurios #line
markers into the preprocessor output (see comment in the actual patch).

diff --git a/ncurses/base/MKlib_gen.sh b/ncurses/base/MKlib_gen.sh
index b91398c..9e41cea 100755
--- a/ncurses/base/MKlib_gen.sh
+++ b/ncurses/base/MKlib_gen.sh
@@ -66,6 +66,23 @@ preprocessor="$1 -DNCURSES_INTERNALS -I../include"
 AWK="$2"
 USE="$3"
 
+# A patch discussed here:
+#	https://gcc.gnu.org/ml/gcc-patches/2014-06/msg02185.html
+# introduces spurious #line markers into the preprocessor output.  The result
+# appears in gcc 5.0 and (with modification) in 5.1, making it necessary to
+# determine if we are using gcc, and if so, what version because the proposed
+# solution uses a nonstandard option.
+PRG=`echo "$1" | sed -e 's/[[:space:]].*$//'`
+FSF=`"$PRG" --version 2>/dev/null | fgrep "Free Software Foundation" | head -n 1`
+ALL=`"$PRG" -dumpversion 2>/dev/null `
+ONE=`echo "$ALL" | sed -e 's/\..*$//'`
+if test -n "$FSF" && test -n "$ALL" && test -n "$ONE" ; then
+	if test $ONE -ge 5 ; then
+		echo ".. adding -P option to work around $PRG $ALL" >&2
+		preprocessor="$preprocessor -P"
+	fi
+fi
+
 PID=$$
 ED1=sed1_${PID}.sed
 ED2=sed2_${PID}.sed