[build] add convenience script for ASan builds

Sometimes when ASan support is wanted for fwknop, the following compile
error can be generated. This script provides a means to solve this.

fwknop-spa_comm.o: In function `send_spa_packet_http':
/home/mbr/git/fwknop.git/client/spa_comm.c:516: undefined reference to `rpl_malloc'
../lib/.libs/libfko.so: undefined reference to `rpl_realloc'

Makefile.am

@@ -74,6 +74,7 @@ EXTRA_DIST = \
     extras/ramdisk/ramdisk-create.sh \
     extras/ramdisk/ramdisk-create-osx.sh \
     extras/console-qr/console-qr.sh \
+    extras/sanitizer/asan-build.sh \
     fwknop.spec \
     iphone/main.m \
     iphone/Fwknop.xcodeproj \

extras/sanitizer/asan-build.sh

@@ -0,0 +1,21 @@
+#!/bin/sh -x
+
+#
+# In some cases when enabling Google's Address Sanitizer, errors like the
+# following can be generated. This script provides a workaround.
+#
+# fwknop-spa_comm.o: In function `send_spa_packet_http':
+# /home/mbr/git/fwknop.git/client/spa_comm.c:516: undefined reference to `rpl_malloc'
+# ../lib/.libs/libfko.so: undefined reference to `rpl_realloc'
+#
+
+if [ -x ./configure ]; then
+    export ac_cv_func_malloc_0_nonnull=yes
+    export ac_cv_func_realloc_0_nonnull=yes
+    ./autogen.sh
+    ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/run --enable-asan-support $@
+    make clean
+    make
+else
+    echo "[*] Execute from the fwknop top level sources directory"
+fi