Workaround for a breaking change in GNU make 4.3. for libvmod-re2

dpkg/libvmod-re2/debian/rules

@@ -4,12 +4,21 @@ DH_VERBOSE=1
 export RE2_CFLAGS=-pthread
 export RE2_LIBS=-pthread -lre2
 
-VMOD_ABI = $(shell printf '\#include "vrt.h"\nvarnishabi- VRT_MAJOR_VERSION . VRT_MINOR_VERSION\n' \
-        | cpp - $(shell pkg-config --cflags varnishapi) \
-        | sed -e '/^varnishabi-/!d' -e 's/U//g' -e 's/ //g')
-VMOD_strictABI = $(shell printf '\#include "vmod_abi.h"\nVMOD_ABI_Version\n' \
-        | cpp - $(shell pkg-config --cflags varnishapi) \
-        | sed -e '/^"/!d' -e 's/\"//g' -e 's/^.* /varnishabi-strict-/')
+# Workaround for a breaking change in GNU make 4.3.
+H := \#
+
+# Extract VMOD_ABI version, this is used for building vmods using the official
+# VMOD API
+VMOD_ABI = $(shell printf '$(H)include "vdef.h"\n$(H)include "vrt.h"\nvarnishabi- VRT_MAJOR_VERSION . VRT_MINOR_VERSION\n' \
+           | cpp - -Iinclude \
+           | sed -e '/^varnishabi-/!d' -e 's/U//g' -e 's/ //g')
+
+# Extract VMOD_strictABI, which refers to the exact build of varnish. This is
+# used for old style vmods bypassing the VMOD API, accessing the internal data
+# structures directly.
+VMOD_strictABI = $(shell printf '$(H)include "vcs_version.h"\nVCS_Version\n' \
+                 | cpp - -Iinclude \
+                 | sed -e '/^"/!d' -e 's/\"//g' -e 's/^/varnishabi-strict-/')
 
 override_dh_auto_configure:
 	./autogen.sh