test: enable LSan for certain wrapped binaries

So we're able to detect memory leaks in our NSS modules.

An example after introducing a memory leak in nss-myhostname.c:

testsuite-71.sh[2881]: =================================================================
testsuite-71.sh[2881]: ==2880==ERROR: LeakSanitizer: detected memory leaks
testsuite-71.sh[2881]: Direct leak of 2 byte(s) in 1 object(s) allocated from:
testsuite-71.sh[2881]:     #0 0x7fa28907243b in strdup (/usr/lib64/libasan.so.8.0.0+0x7243b)
testsuite-71.sh[2881]:     #1 0x7fa286a7bc10 in gethostname_full ../src/basic/hostname-util.c:67
testsuite-71.sh[2881]:     #2 0x7fa286a74af9 in gethostname_malloc ../src/basic/hostname-util.h:24
testsuite-71.sh[2881]:     #3 0x7fa286a756f4 in _nss_myhostname_gethostbyname4_r ../src/nss-myhostname/nss-myhostname.c:79
testsuite-71.sh[2881]:     #4 0x7fa288f17588 in getaddrinfo (/lib64/libc.so.6+0xf4588)
testsuite-71.sh[2881]:     #5 0x7fa2890a4d93 in __interceptor_getaddrinfo.part.0 (/usr/lib64/libasan.so.8.0.0+0xa4d93)
testsuite-71.sh[2881]:     #6 0x55a54b2b7159 in ahosts_keys_int.part.0 (/usr/bin/getent.orig+0x4159)
testsuite-71.sh[2881]: SUMMARY: AddressSanitizer: 2 byte(s) leaked in 1 allocation(s).

(cherry picked from commit 2b5e786)
(cherry picked from commit 5a29fbb)
(cherry picked from commit 7d667e5)

test/test-functions

@@ -2449,6 +2449,7 @@ inst_binary() {
     # DSOs provided by systemd
     local systemd_so_regex='/(libudev|libsystemd.*|.+[\-_]systemd([\-_].+)?|libnss_(mymachines|myhostname|resolve)).so'
     local wrap_binary=0
+    local enable_lsan=0
     # I love bash!
     while read -r line; do
         [[ "$line" = 'not a dynamic executable' ]] && break
@@ -2490,6 +2491,14 @@ inst_binary() {
     bin_rx='/(agetty|chown|curl|delv|dig|getfacl|getent|login|ls|mkfs\.[a-z0-9]+|mksquashfs|mkswap|setpriv|stat|su|tar|useradd|userdel)$'
     if get_bool "$IS_BUILT_WITH_ASAN" && [[ "$bin" =~ $bin_rx ]]; then
         wrap_binary=1
+        # Ugh, so we want to disable LSan in most cases for the wrapped binaries, since
+        # we don't care about memory leaks in such binaries. However, in certain cases
+        # the external binary is the only interface for the systemd code, like for
+        # the systemd NSS modules, where we want to detect memory leaks. So let's
+        # do another check to decide if we want to enable LSan for given binary.
+        if [[ "$bin" =~ /getent$ ]]; then
+            enable_lsan=1
+        fi
     fi
 
     # If the target binary is built with ASan support, we don't need to wrap
@@ -2507,7 +2516,7 @@ inst_binary() {
 export LD_PRELOAD="$ASAN_RT_PATH"
 # Disable LSan to speed things up, since we don't care about leak reports
 # from 'external' binaries
-export ASAN_OPTIONS=detect_leaks=0
+export ASAN_OPTIONS=detect_leaks=$enable_lsan
 # Set argv[0] to the original binary name without the ".orig" suffix
 exec -a "\$0" -- "${target}.orig" "\$@"
 EOF