Makefile: use git describe --always to make version.cc

If git-describe fails, an empty string is assigned to CS_VERSION, which
breaks the regression tests that expect csdiff version to be available.
Unfortunately, `git describe --tags` is not compatible with checkout@v3
GitHub Action.

Author: kdudka

.github/workflows/ci.yml

@@ -25,9 +25,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
 
-      - name: Fetch tags to make git-describe work
-        run: git fetch --tags origin
-
       - name: '[clang] Install a default version for Ubuntu ${{ matrix.version }}'
         if: matrix.compiler == 'clang++'
         run: |

Makefile

@@ -28,9 +28,6 @@ CMAKE_BUILD_TYPE ?= RelWithDebInfo
 	fast install version.cc src/version.cc
 
 all: version.cc
-	git describe --tags
-	git describe --tags | sed -e "s/^csdiff-//"
-	git describe --tags | sed -e "s/^csdiff-//" -e "s/-.*-/.$$(git log --pretty="%cd" --date=iso -1 | tr -d ":-" | tr " " . | cut -d. -f 1,2)./"
 	cat src/version.cc
 	mkdir -p csdiff_build
 	cd csdiff_build && $(CMAKE) \
@@ -68,7 +65,7 @@ version.cc: src/version.cc
 
 src/version.cc:
 	@if test -e .git; then \
-		cmd='git describe --tags | sed -e "s/^csdiff-//" -e "s/-.*-/.$$(git log --pretty="%cd" --date=iso -1 | tr -d ":-" | tr " " . | cut -d. -f 1,2)./"'; \
+		cmd='git describe --always | sed -e "s/^csdiff-//" -e "s/-.*-/.$$(git log --pretty="%cd" --date=iso -1 | tr -d ":-" | tr " " . | cut -d. -f 1,2)./"'; \
 	else \
 		cmd='basename $$(readlink -f .) | cut -f2 -d-'; \
 	fi \