Use the _ONCE variation of AC_CHECKs where applicable.

When we're unconditionally looking for a function, or an header file,
without particular libraries set, or with found/not-found conditional code,
we can save ~1K lines in the final configure script by using the _ONCE
variant.

This makes sure that for each header of function, the check is done exactly
once and never more, reducing the amount of code that has to be generated
and executed.

diff --git a/configure.ac b/configure.ac
index 37b9fc5..a3f9f0e 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -301,7 +301,7 @@ AM_CONDITIONAL(OS_IS_WIN32, test "x$os_is_win32" = "x1")
 AC_HEADER_STDC
 
 # POSIX
-AC_CHECK_HEADERS([arpa/inet.h glob.h grp.h netdb.h netinet/in.h \
+AC_CHECK_HEADERS_ONCE([arpa/inet.h glob.h grp.h netdb.h netinet/in.h \
     netinet/in_systm.h netinet/tcp.h poll.h pwd.h sched.h \
     sys/mman.h sys/resource.h sys/select.h sys/socket.h sys/wait.h \
     sys/uio.h syslog.h sys/dl.h dlfcn.h linux/sockios.h])
@@ -325,23 +325,23 @@ AC_CHECK_HEADERS([linux/input.h], [HAVE_EVDEV=1], [HAVE_EVDEV=0])
 
 AM_CONDITIONAL([HAVE_EVDEV], [test "x$HAVE_EVDEV" = "x1"])
 
-AC_CHECK_HEADERS([sys/prctl.h])
+AC_CHECK_HEADERS_ONCE([sys/prctl.h])
 
 # Solaris
-AC_CHECK_HEADERS([sys/filio.h])
+AC_CHECK_HEADERS_ONCE([sys/filio.h])
 
 # Windows
-AC_CHECK_HEADERS([windows.h winsock2.h ws2tcpip.h])
+AC_CHECK_HEADERS_ONCE([windows.h winsock2.h ws2tcpip.h])
 
 # NetBSD
-AC_CHECK_HEADERS([sys/atomic.h])
+AC_CHECK_HEADERS_ONCE([sys/atomic.h])
 
 # Other
-AC_CHECK_HEADERS([sys/ioctl.h])
-AC_CHECK_HEADERS([byteswap.h])
-AC_CHECK_HEADERS([sys/syscall.h])
-AC_CHECK_HEADERS([sys/eventfd.h])
-AC_CHECK_HEADERS([execinfo.h])
+AC_CHECK_HEADERS_ONCE([sys/ioctl.h])
+AC_CHECK_HEADERS_ONCE([byteswap.h])
+AC_CHECK_HEADERS_ONCE([sys/syscall.h])
+AC_CHECK_HEADERS_ONCE([sys/eventfd.h])
+AC_CHECK_HEADERS_ONCE([execinfo.h])
 
 #### Typdefs, structures, etc. ####
 
@@ -395,13 +395,13 @@ AC_CHECK_FUNCS([getopt_long], [], [AC_CHECK_LIB([iberty], [getopt_long])])
 #### Check for functions ####
 
 # ISO
-AC_CHECK_FUNCS([lrintf strtof])
+AC_CHECK_FUNCS_ONCE([lrintf strtof])
 
 # POSIX
 AC_FUNC_FORK
 AC_FUNC_GETGROUPS
 AC_FUNC_SELECT_ARGTYPES
-AC_CHECK_FUNCS([chmod chown clock_gettime getaddrinfo getgrgid_r getgrnam_r \
+AC_CHECK_FUNCS_ONCE([chmod chown clock_gettime getaddrinfo getgrgid_r getgrnam_r \
     getpwnam_r getpwuid_r gettimeofday getuid inet_ntop inet_pton mlock nanosleep \
     pipe posix_fadvise posix_madvise posix_memalign setpgid setsid shm_open \
     sigaction sleep sysconf pthread_setaffinity_np])
@@ -410,20 +410,20 @@ AC_CHECK_FUNCS([mkfifo], [HAVE_MKFIFO=1], [HAVE_MKFIFO=0])
 AM_CONDITIONAL(HAVE_MKFIFO, test "x$HAVE_MKFIFO" = "x1")
 
 # X/OPEN
-AC_CHECK_FUNCS([readlink])
+AC_CHECK_FUNCS_ONCE([readlink])
 
 # SUSv2
-AC_CHECK_FUNCS([ctime_r usleep])
+AC_CHECK_FUNCS_ONCE([ctime_r usleep])
 
 # SUSv3
-AC_CHECK_FUNCS([strerror_r])
+AC_CHECK_FUNCS_ONCE([strerror_r])
 
 # BSD
-AC_CHECK_FUNCS([lstat])
+AC_CHECK_FUNCS_ONCE([lstat])
 
 # Non-standard
 
-AC_CHECK_FUNCS([setresuid setresgid setreuid setregid seteuid setegid ppoll strsignal sig2str strtof_l])
+AC_CHECK_FUNCS_ONCE([setresuid setresgid setreuid setregid seteuid setegid ppoll strsignal sig2str strtof_l])
 
 AC_FUNC_ALLOCA
 
@@ -456,7 +456,7 @@ AC_DEFINE_UNQUOTED(PA_CFLAGS,"$CFLAGS", [The CFLAGS used during compilation])
 AC_SYS_LARGEFILE
 
 # Check for open64 to know if the current system does have open64() and similar functions
-AC_CHECK_FUNCS([open64])
+AC_CHECK_FUNCS_ONCE([open64])
 
 #### [lib]iconv ####
 
@@ -535,7 +535,7 @@ fi
 
 #### Valgrind (optional) ####
 
-AC_CHECK_HEADERS([valgrind/memcheck.h])
+AC_CHECK_HEADERS_ONCE([valgrind/memcheck.h])
 
 #### Sound file ####