Testing is simple.  Make sure nscd is not running on the machine and that the mysql server is not in the hosts file
but is in DNS. 

Test page.
<?
$db=mysql_connect("server.com","user","pass");
mysql_select_db("database",$db);
$result=mysql_query("select FirstName from Users");
while ( $row=mysql_fetch_row($result)) {
echo ("$row[0]\n");
}
?>

Standalone it works fine.  When run through the webserver
it hangs forever getting stuck in the gethostbyname from
the mysql_connect.  I even changed the libmysqlclient 
libary to the libmysqlclient_r library in the configure and verified it was being used with a ldd of libphp4.so.

The webserver is apache 2.0.35 configured with these options:
./configure --prefix=/prod/apache --enable-layout=Apache --enable-ssl --enable-vhost-alias --enable-proxy --enable-rewrite --enable-so --with-mpm=worker --disable-userdir

The php module is configured with:
./configure  --prefix=/prod/apache/php --with-apxs2=/prod/apache/bin/apxs --with-openssl --with-zlib --with-gd --with-java=/usr/java --with-mysql=/prod/mysql --with-readline --enable-memory-limit

It will work if nscd is on, or if /etc/hosts contains the name of the machine that needs to be resolved.

#0  0x402bdba5 in __sigsuspend (set=0x40b3236c) at ../sysdeps/unix/sysv/linux/sigsuspend.c:45
#1  0x402821d9 in __pthread_wait_for_restart_signal (self=0x40b34be0) at pthread.c:969
#2  0x40283a2c in __pthread_lock (lock=0x4001649c, self=0x40b34be0) at spinlock.c:149
#3  0x40280d46 in __pthread_mutex_lock (mutex=0x4001648c) at mutex.c:109
#4  0x403a8e40 in _dl_open (file=0x40b3262c "libnss_dns.so.2", mode=1, caller=0x0) at dl-open.c:401
#5  0x403a9cd1 in do_dlopen (ptr=0x40b325fc) at dl-libc.c:78
#6  0x4000d7c3 in _dl_catch_error (objname=0x40b325f4, errstring=0x40b325f8, operate=0x403a9cb0 <do_dlopen>, args=0x40b325fc)
    at dl-error.c:152
#7  0x403a9b7c in __libc_dlopen (__name=0x40b3262c "libnss_dns.so.2") at dl-libc.c:42
#8  0x4038aeef in __nss_lookup_function (ni=0x8130940, fct_name=0x403be4ee "gethostbyname_r") at nsswitch.c:340
#9  0x4038b911 in __nss_next (ni=0x40b326dc, fct_name=0x403be4ee "gethostbyname_r", fctp=0x40b326e0, status=-1, all_values=0)
    at nsswitch.c:194
#10 0x4038e1dd in __gethostbyname_r (name=0x82322fc "database.mycompany.com", resbuf=0x40b3316c, buffer=0x40b3296c "\177", 
    buflen=2048, result=0x40b3271c, h_errnop=0x40b32768) at ../nss/getXXbyYY_r.c:215
#11 0x405da13c in my_gethostbyname_r () from /prod/mysql/lib/mysql/libmysqlclient_r.so.10
#12 0x405d1f69 in mysql_real_connect () from /prod/mysql/lib/mysql/libmysqlclient_r.so.10
#13 0x4049b0ea in php_mysql_do_connect (ht=3, return_value=0x8236ccc, this_ptr=0x0, return_value_used=1, tsrm_ls=0x81bcdc8, 
    persistent=0) at php_mysql.c:662
#14 0x4049b2e4 in zif_mysql_connect (ht=3, return_value=0x8236ccc, this_ptr=0x0, return_value_used=1, tsrm_ls=0x81bcdc8)
    at php_mysql.c:714
#15 0x404652e8 in execute (op_array=0x8232294, tsrm_ls=0x81bcdc8) at ./zend_execute.c:1598
#16 0x40473f92 in zend_execute_scripts (type=8, tsrm_ls=0x81bcdc8, retval=0x0, file_count=3) at zend.c:810
#17 0x4048163a in php_execute_script (primary_file=0x40b348bc, tsrm_ls=0x81bcdc8) at main.c:1381
#18 0x4047df8d in php_output_filter (f=0x822d290, bb=0x822d4a0) at sapi_apache2.c:401
#19 0x080aa99f in ap_pass_brigade (next=0x822d290, bb=0x822d380) at util_filter.c:534
#20 0x080b0a5b in default_handler (r=0x81fbe60) at core.c:3247
#21 0x080a1236 in ap_run_handler (r=0x81fbe60) at config.c:193
#22 0x080a16a1 in ap_invoke_handler (r=0x81fbe60) at config.c:373
#23 0x0808a5d7 in ap_process_request (r=0x81fbe60) at http_request.c:261
#24 0x08086cb5 in ap_process_http_connection (c=0x81c1428) at http_core.c:291
#25 0x080a9372 in ap_run_process_connection (c=0x81c1428) at connection.c:85
#26 0x0809e876 in process_socket (p=0x81c1318, sock=0x81c1350, my_child_num=0, my_thread_num=0, bucket_alloc=0x81bf2a8)
    at worker.c:613
#27 0x0809ed73 in worker_thread (thd=0x8142590, dummy=0x81bcdc8) at worker.c:886
#28 0x4003ae34 in dummy_worker (opaque=0x8142590) at thread.c:127
#29 0x4027fc6f in pthread_start_thread (arg=0x40b34be0) at manager.c:284
#30 0x4027fd5f in pthread_start_thread_event (arg=0x40b34be0) at manager.c:308