examples: change $(pwd) to "${PWD}"

Make a minor fix to the build scripts to quote the pwd in case it has a
space in it.  While we're at it, use (POSIX specified) ${PWD} instead of
potentially shelling out to $(pwd).

Thanks to Pragyan for the suggestion.

Signed-off-by: Allison Karlitskaya <[email protected]>

Author: allisonkarlitskaya

examples/unified-secureboot/build

@@ -41,7 +41,7 @@ fi
 mkdir tmp/internal-sysroot
 podman build \
     --iidfile=tmp/iid \
-    -v $(pwd)/tmp/internal-sysroot:/tmp/sysroot:z,U \
+    -v "${PWD}/tmp/internal-sysroot:/tmp/sysroot:z,U" \
     --secret=id=key,src=secureboot/db.key \
     --secret=id=cert,src=secureboot/db.crt \
     .

examples/unified/build

@@ -25,7 +25,7 @@ mkdir -p tmp/sysroot/composefs
 mkdir tmp/internal-sysroot
 podman build \
     --iidfile=tmp/iid \
-    -v $(pwd)/tmp/internal-sysroot:/tmp/sysroot:z,U \
+    -v "${PWD}/tmp/internal-sysroot:/tmp/sysroot:z,U" \
     .
 
 IMAGE_ID="$(sed s/sha256:// tmp/iid)"