build: Detect missed pkg-config early

configure.ac

@@ -14,6 +14,12 @@ AC_CONFIG_HEADERS([src/config/bitcoin-config.h])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
 
+m4_ifndef([PKG_PROG_PKG_CONFIG], [AC_MSG_ERROR([PKG_PROG_PKG_CONFIG macro not found. Please install pkg-config and re-run autogen.sh])])
+PKG_PROG_PKG_CONFIG
+if test "x$PKG_CONFIG" = x; then
+  AC_MSG_ERROR([pkg-config not found])
+fi
+
 BITCOIN_DAEMON_NAME=bitcoind
 BITCOIN_GUI_NAME=bitcoin-qt
 BITCOIN_CLI_NAME=bitcoin-cli
@@ -677,12 +683,6 @@ case $host in
      ;;
 esac
 
-m4_ifndef([PKG_PROG_PKG_CONFIG], [AC_MSG_ERROR([PKG_PROG_PKG_CONFIG macro not found. Please install pkg-config and re-run autogen.sh])])
-PKG_PROG_PKG_CONFIG
-if test "x$PKG_CONFIG" = x; then
-  AC_MSG_ERROR([pkg-config not found])
-fi
-
 if test x$use_extended_functional_tests != xno; then
   AC_SUBST(EXTENDED_FUNCTIONAL_TESTS, --extended)
 fi