Merge #10766: Building Environment: Set ARFLAGS to cr

912da1dcc Use AC_ARG_VAR to set ARFLAGS. (René Nyffenegger)

Pull request description:

  Override the default of ARFLAGS of `cru` to `cr`.

  When building, ar produces a warning for each archive, for example
  ```
    AR       libbitcoin_server.a
  /usr/bin/ar: `u' modifier ignored since `D' is the default (see `U')

  ```
  Since `u` is the default anyway, it cannot hurt to remove it.

Tree-SHA512: 7466764f847b70f0f67db25dac87a7794477abf1997cb946682f394fe80ae86ac3ed52cbadb35f0c18a87467755bde5a5158430444cd26fb60fa363cc7bd486d

configure.ac

@@ -19,6 +19,12 @@ BITCOIN_GUI_NAME=bitcoin-qt
 BITCOIN_CLI_NAME=bitcoin-cli
 BITCOIN_TX_NAME=bitcoin-tx
 
+dnl Unless the user specified ARFLAGS, force it to be cr
+AC_ARG_VAR(ARFLAGS, [Flags for the archiver, defaults to <cr> if not set])
+if test "x${ARFLAGS+set}" != "xset"; then
+  ARFLAGS="cr"
+fi
+
 AC_CANONICAL_HOST
 
 AH_TOP([#ifndef BITCOIN_CONFIG_H])
@@ -1285,4 +1291,5 @@ echo "  CPPFLAGS      = $CPPFLAGS"
 echo "  CXX           = $CXX"
 echo "  CXXFLAGS      = $CXXFLAGS"
 echo "  LDFLAGS       = $LDFLAGS"
+echo "  ARFLAGS       = $ARFLAGS"
 echo