Merge bitcoin#28755: build: remove duplicate -lminiupnpc linking

b74e449 build: remove potential for duplciate natpmp linking (fanquake)
4e95096 build: remove duplicate -lminiupnpc linking (fanquake)

Pull request description:

  Having the link check in the header check loop means we get `-lminiupnpc -lminiupnpc -lminiupnpc` on the link line.
  This is unnecessary, and results in warnings, i.e:
  ```bash
  ld: warning: ignoring duplicate libraries: '-levent', '-lminiupnpc'
  ld: warning: ignoring duplicate libraries: '-levent', '-lminiupnpc'
  ld: warning: ignoring duplicate libraries: '-levent', '-lminiupnpc'
  ```

  These warnings have been occurring since the new macOS linker released with Xcode 15, and also came up in hebasto#34.

  There are other duplicate lib issues, i.e with `-levent` + `-levent_pthreads -levent`, but those are less straight forward to solve, and won't be included here.

ACKs for top commit:
  jonatack:
    ACK b74e449
  hebasto:
    ACK b74e449, it fixes one issue mentioned in hebasto#34 (comment).
  TheCharlatan:
    ACK b74e449
  theuni:
    ACK b74e449

Tree-SHA512: 987a56ef17cbaf273cb672c41016f3f615b16889317325a9e88135d0c41f01af3840ad44a6f811a7df97f5873c9cd957e60aaa1b99bd408b17b4b1ffe2c68f36

Author: fanquake

configure.ac

@@ -1424,15 +1424,13 @@ dnl Check for libminiupnpc (optional)
 if test "$use_upnp" != "no"; then
   TEMP_CPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS $MINIUPNPC_CPPFLAGS"
-  AC_CHECK_HEADERS(
-    [miniupnpc/miniupnpc.h miniupnpc/upnpcommands.h miniupnpc/upnperrors.h],
-    [AC_CHECK_LIB([miniupnpc], [upnpDiscover], [MINIUPNPC_LIBS="$MINIUPNPC_LIBS -lminiupnpc"], [have_miniupnpc=no], [$MINIUPNPC_LIBS])],
-    [have_miniupnpc=no]
-  )
+  AC_CHECK_HEADERS([miniupnpc/miniupnpc.h miniupnpc/upnpcommands.h miniupnpc/upnperrors.h], [], [have_miniupnpc=no])
 
-  dnl The minimum supported miniUPnPc API version is set to 17. This excludes
-  dnl versions with known vulnerabilities.
   if test "$have_miniupnpc" != "no"; then
+    AC_CHECK_LIB([miniupnpc], [upnpDiscover], [MINIUPNPC_LIBS="$MINIUPNPC_LIBS -lminiupnpc"], [have_miniupnpc=no], [$MINIUPNPC_LIBS])
+
+    dnl The minimum supported miniUPnPc API version is set to 17. This excludes
+    dnl versions with known vulnerabilities.
     AC_MSG_CHECKING([whether miniUPnPc API version is supported])
     AC_PREPROC_IFELSE([AC_LANG_PROGRAM([[
         @%:@include <miniupnpc/miniupnpc.h>
@@ -1457,9 +1455,12 @@ dnl Check for libnatpmp (optional).
 if test "$use_natpmp" != "no"; then
   TEMP_CPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS $NATPMP_CPPFLAGS"
-  AC_CHECK_HEADERS([natpmp.h],
-                   [AC_CHECK_LIB([natpmp], [initnatpmp], [NATPMP_LIBS="$NATPMP_LIBS -lnatpmp"], [have_natpmp=no], [$NATPMP_LIBS])],
-                   [have_natpmp=no])
+  AC_CHECK_HEADERS([natpmp.h], [], [have_natpmp=no])
+
+  if test "$have_natpmp" != "no"; then
+    AC_CHECK_LIB([natpmp], [initnatpmp], [NATPMP_LIBS="$NATPMP_LIBS -lnatpmp"], [have_natpmp=no], [$NATPMP_LIBS])
+  fi
+
   CPPFLAGS="$TEMP_CPPFLAGS"
 fi