abicheck.sh: implement --refresh-if option as documented.

Also change exit status to nonzero if there is no abifile and --refresh or --refresh-if were not specified.

.github/workflows/pkgcheck.yml

@@ -128,7 +128,7 @@ jobs:
       # macOS runner does not contain abigail
       if: runner.os != 'macOS'
       run: |
-        sh test/abicheck.sh --refresh_if
+        sh test/abicheck.sh --refresh-if
       env:
         CC: ${{ matrix.compiler }}
         CXX: ${{ matrix.cxx-compiler }}
@@ -143,7 +143,7 @@ jobs:
       # macOS runner does not contain abigail
       if: runner.os != 'macOS'
       run: |
-        sh test/abicheck.sh --zlib-compat --refresh_if
+        sh test/abicheck.sh --zlib-compat --refresh-if
       env:
         CC: ${{ matrix.compiler }}
         CXX: ${{ matrix.cxx-compiler }}

test/abicheck.md

@@ -29,7 +29,7 @@ means someone has to check out and build
 the previous source tree and extract its .abi
 using abidw.  This can be slow.
 
-If you don't mind the slowness, run abicheck.sh --refresh_if,
+If you don't mind the slowness, run abicheck.sh --refresh-if,
 and it will download and build the reference version
 and extract the .abi on the spot if needed.
 (FIXME: should this be the default?)

test/abicheck.sh

@@ -49,7 +49,7 @@ do
   --refresh)
     refresh=true
     ;;
-  --refresh_if)
+  --refresh-if)
     refresh_if=true
     ;;
   --help)
@@ -134,12 +134,10 @@ then
   # caching abi files in git (but that would slow builds down).
 fi
 
-if test -f "$ABIFILE"
+if ! test -f "$ABIFILE"
 then
-  ABIFILE="$ABIFILE"
-else
-  echo "abicheck: SKIP: $ABIFILE not found; rerun with --refresh or --refresh_if"
-  exit 0
+  echo "abicheck: SKIP: $ABIFILE not found; rerun with --refresh or --refresh-if"
+  exit 1
 fi
 
 # Build unstripped, uninstalled, very debug shared library