grep: don't use _FORTIFY_SOURCE=2 for debug builds

packages/grep/build.sh

@@ -6,3 +6,16 @@ TERMUX_PKG_VERSION=3.3
 TERMUX_PKG_REVISION=1
 TERMUX_PKG_SRCURL=https://mirrors.kernel.org/gnu/grep/grep-${TERMUX_PKG_VERSION}.tar.xz
 TERMUX_PKG_SHA256=b960541c499619efd6afe1fa795402e4733c8e11ebf9fafccc0bb4bccdc5b514
+
+termux_step_pre_configure() {
+	if [ "$TERMUX_DEBUG" == "true" ]; then
+		# When doing debug build, -D_FORTIFY_SOURCE=2 gives this error:
+		# /home/builder/.termux-build/_cache/19b-aarch64-24-v5/bin/../sysroot/usr/include/bits/fortify/stdio.h:51:53: error: use of undeclared identifier '__USE_FORTIFY_LEVEL'
+		# return __builtin___vsnprintf_chk(dest, size, 0, __bos(dest), format, ap);
+		#                                                 ^
+		# lib/cdefs.h:123:48: note: expanded from macro '__bos'
+		# #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
+		#                                                ^
+		export CFLAGS=${CFLAGS/-D_FORTIFY_SOURCE=2/}
+	fi
+}