test: fix a yet another pipefail + pipe race

Basically the same scenario as in
a33e2692e162671f0d97856ad2f49a2620a1ec10, where `awk` exits as soon
as it finds a match, thus sending SIGPIPE to `ldd` if it's not fast
enough. That, in combination with `set -o pipefail` causes random &
unexpected fails, like:

```
No journal files were found.
-rw-r----- 1 root root 16777216 Apr 30 10:31
/var/tmp/TEST-01-BASIC_sanitizers-nspawn/system.journal
TEST-01-BASIC RUN: Basic systemd setup [OK]
systemd is not linked against the ASan DSO
gcc does this by default, for clang compile with -shared-libasan
make: *** [Makefile:2: clean-again] Error 1
make: Leaving directory '/build/test/TEST-01-BASIC'
```

1 files changed, 2 insertions, 2 deletions

diff --git a/test/test-functions b/test/test-functions
index 8bae7a9911..da1e20f492 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -227,10 +227,10 @@ if [[ "$IS_BUILT_WITH_ASAN" = "yes" ]]; then
     QEMU_SMP="${QEMU_SMP:-4}"
 
     # We need to correctly distinguish between gcc's and clang's ASan DSOs.
-    if ASAN_RT_NAME="$(ldd "$SYSTEMD" | awk '/libasan.so/ {x=$1; exit} END {print x; exit x==""}')"; then
+    if ASAN_RT_NAME="$(awk '/libasan.so/ {x=$1; exit} END {print x; exit x==""}' < <(ldd "$SYSTEMD"))"; then
         ASAN_COMPILER=gcc
         ASAN_RT_PATH="$(readlink -f "$(${CC:-gcc} --print-file-name "$ASAN_RT_NAME")")"
-    elif ASAN_RT_NAME="$(ldd "$SYSTEMD" | awk '/libclang_rt.asan/ {x=$1; exit} END {print x; exit x==""}')"; then
+    elif ASAN_RT_NAME="$(awk '/libclang_rt.asan/ {x=$1; exit} END {print x; exit x==""}' < <(ldd "$SYSTEMD"))"; then
         ASAN_COMPILER=clang
         ASAN_RT_PATH="$(readlink -f "$(${CC:-clang} --print-file-name "$ASAN_RT_NAME")")"