d/rules: Accept dots in the extended BINNMU rule

Builds in the v2019 OBS were failing in the gencontrol target since the build
suffix used there is `v2019.0b1` and the regest was not matching the `.` dot.

This was not an issue in the `v2020dev0` project since its build suffix does
not contain dots:

    $ VERSION=4.19.37-5co1bv2020dev0b1; echo "$VERSION" | sed -rne 's,[^b]*b([a-z0-9]+)$$,\1,p'
    v2020dev0b1
    $ VERSION=4.19.37-5co1bv2019.0b1; echo "$VERSION" | sed -rne 's,[^b]*b([a-z0-9]+)$$,\1,p'
    4.19.37-5co1b1 # ARGH
    $ VERSION=4.19.37-5co1bv2019.0b1; echo "$VERSION" | sed -rne 's,[^b]*b([a-z0-9.]+)$$,\1,p'
    v2019.0b1
    $ VERSION=4.19.37-5co1bv2020dev0b1; echo "$VERSION" | sed -rne 's,[^b]*b([a-z0-9.]+)$$,\1,p'
    v2020dev0b1

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

debian/rules

@@ -4,7 +4,7 @@ SHELL    := sh -e
 SOURCE := $(shell dpkg-parsechangelog -SSource)
 VERSION := $(shell dpkg-parsechangelog -SVersion)
 VERSION_UPSTREAM := $(shell echo "$(VERSION)" | sed -e 's,-[^-]*$$,,')
-VERSION_BINNMU := $(shell echo "$(VERSION)" | sed -rne 's,[^b]*b([a-z0-9]+)$$,\1,p')
+VERSION_BINNMU := $(shell echo "$(VERSION)" | sed -rne 's,[^b]*b([a-z0-9.]+)$$,\1,p')
 VERSION_SOURCE := $(patsubst %b$(VERSION_BINNMU),%,$(VERSION))
 
 include /usr/share/dpkg/architecture.mk