Description of problem:
In commit https://github.com/lnykryn/systemd-rhel/commit/5ec508cc5c13d831c93ce98d84b1d9cedb0117a7 we have added two new APIs. These APIs are now used internally from journalctl. Despite being marked as _public_, we do not export them because they've never been added to respective .sym file. There are applications that would like to make use of them, e.g. rsyslog's imjournal module.

Version-Release number of selected component (if applicable):
systemd-219-30.el7_3.6

How reproducible:
always

Steps to Reproduce:
1. yum install -y systemd-devel
2. cat > /tmp/sd-journal-has-persistent-files.c << EOF
#include <stdio.h>
#include <systemd/sd-journal.h>

int main() {
        int r;
        sd_journal *j;
        
        sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
        
        r = sd_journal_has_persistent_files(j);
        
        sd_journal_close(j);
        
        return r;
}
EOF
3. gcc /tmp/sd-journal-has-persistent-files.c -lsystemd
4. ./a.out
5. echo $?

Actual results:
Compilation (step 3) returns following error,
/tmp/cco975MF.o: In function `main':
sd-journal-has-persistent.c:(.text+0x21): undefined reference to `sd_journal_has_persistent_files'
collect2: error: ld returned 1 exit status

Expected results:
Compilation and execution are successful

Additional info:
We need to backport https://github.com/systemd/systemd/commit/9a07f779bbeacc3358d405f6cf583506aaf655ae or came up with similar patch due to different versioning between upstream and RHEL7.