Merge bitcoin#21400: build: Fix regression introduced in bitcoin#21363

ffdd7de build, qt: Fix regression introduced in bitcoin#21363 (Hennadii Stepanov)

Pull request description:

  After bitcoin#21363 the `_BITCOIN_QT_CHECK_STATIC_PLUGIN` never fails due to the ill-formed code.

  Sorry for breaking it.

ACKs for top commit:
  fanquake:
    ACK ffdd7de

Tree-SHA512: 0af3334af5332f3b349dba219565ee336090541c2c4fae53d7dc4dd2aa05291b3c7c13bfc506219f642fb854f3c887f0f9621b42d0df68d5d794e0563b2cf5d4

Author: fanquake

build-aux/m4/bitcoin_qt.m4

@@ -306,7 +306,10 @@ AC_DEFUN([_BITCOIN_QT_CHECK_STATIC_PLUGIN], [
   AC_MSG_CHECKING([for $1 ($2)])
   CHECK_STATIC_PLUGINS_TEMP_LIBS="$LIBS"
   LIBS="$2${qt_lib_suffix} $QT_LIBS $LIBS"
-  AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <QtPlugin> Q_IMPORT_PLUGIN($1)]])],
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+      #include <QtPlugin>
+      Q_IMPORT_PLUGIN($1)
+    ]])],
     [AC_MSG_RESULT([yes]); QT_LIBS="$2${qt_lib_suffix} $QT_LIBS"],
     [AC_MSG_RESULT([no]); BITCOIN_QT_FAIL([$1 not found.])])
   LIBS="$CHECK_STATIC_PLUGINS_TEMP_LIBS"