Format shell scripts with shfmt.

All changes in this patch were performed automatically with `shfmt` with
configuration flags specified in `.pre-commit-config.yaml`.

In addition to fixing whitespace the roundtrip through shfmt's AST also
transforms command substitutions

    `cmd`
    # becomes
    $(cmd)

and some redirects

    >&2 echo "msg"
    # becomes
    echo >&2 "msg"

src/script_opt/CPP/single-full-test.sh

@@ -16,7 +16,7 @@ cd $test
 grep -c '^namespace' $gen
 mv $gen $build/
 cd $build
-ninja >& errs || echo build for $1 failed
+ninja >&errs || echo build for $1 failed
 
 export -n ZEEK_GEN_CPP
 cd $test

src/script_opt/CPP/single-test.sh

@@ -15,7 +15,7 @@ cp $build/CPP-hashes.dat .
 grep -c '^namespace' $gen
 mv $gen $build
 cd $build
-ninja >& errs || echo build for $1 failed
+ninja >&errs || echo build for $1 failed
 
 export -n ZEEK_ADD_CPP
 cd $test

src/script_opt/CPP/test-suite-build

@@ -15,4 +15,4 @@ echo >$gen
 grep -c '^namespace' $gen
 mv $gen $so
 cd $build
-ninja >& errs || echo test suite build failed
+ninja >&errs || echo test suite build failed

src/script_opt/CPP/update-single-test.sh

@@ -13,7 +13,7 @@ cp $build/CPP-hashes.dat .
 grep -c '^namespace' $gen
 mv $gen $build/
 cd $build
-ninja >& errs || echo build for $1 failed
+ninja >&errs || echo build for $1 failed
 
 export -n ZEEK_ADD_CPP
 cd $test