build: add an option for enabling glibc back-compat

Using "./configure --enable-glibc-back-compat" will attempt to be
compatible with a target running glibc abi 2.9 and libstdc++ abi 3.4.

configure.ac

@@ -108,6 +108,12 @@ AC_ARG_ENABLE([lcov],
   [use_lcov=yes],
   [use_lcov=no])
 
+AC_ARG_ENABLE([glibc-back-compat],
+  [AS_HELP_STRING([--enable-glibc-back-compat],
+  [enable backwards compatibility with glibc and libstdc++])],
+  [use_glibc_compat=$enableval],
+  [use_glibc_compat=no])
+
 AC_ARG_WITH([protoc-bindir],[AS_HELP_STRING([--with-protoc-bindir=BIN_DIR],[specify protoc bin path])], [protoc_bin_path=$withval], [])
 
 
@@ -319,6 +325,21 @@ fi
 
 AX_CHECK_LINK_FLAG([[-Wl,--large-address-aware]], [LDFLAGS="$LDFLAGS -Wl,--large-address-aware"])
 
+if test x$use_glibc_compat != xno; then
+
+  #__fdelt_chk's params and return type have changed from long unsigned int to long int.
+  # See which one is present here.
+  AC_MSG_CHECKING(__fdelt_chk type)
+  AC_TRY_COMPILE([#define __USE_FORTIFY_LEVEL 2
+                  #include <sys/select.h>
+     extern "C" long unsigned int __fdelt_warn(long unsigned int);],[],
+    [ fdelt_type="long unsigned int"],
+    [ fdelt_type="long int"])
+  AC_MSG_RESULT($fdelt_type)
+  AC_DEFINE_UNQUOTED(FDELT_TYPE, $fdelt_type,[parameter and return value type for __fdelt_chk])
+
+fi
+
 if test x$use_hardening != xno; then
   AX_CHECK_COMPILE_FLAG([-Wstack-protector],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -Wstack-protector"])
   AX_CHECK_COMPILE_FLAG([-fstack-protector-all],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fstack-protector-all"])
@@ -691,6 +712,7 @@ AM_CONDITIONAL([USE_QRCODE], [test x$use_qr = xyes])
 AM_CONDITIONAL([USE_LCOV],[test x$use_lcov == xyes])
 AM_CONDITIONAL([USE_COMPARISON_TOOL],[test x$use_comparison_tool != xno])
 AM_CONDITIONAL([USE_COMPARISON_TOOL_REORG_TESTS],[test x$use_comparison_tool_reorg_test != xno])
+AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
 
 AC_DEFINE(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR, [Major version])
 AC_DEFINE(CLIENT_VERSION_MINOR, _CLIENT_VERSION_MINOR, [Minor version])

src/Makefile.am

@@ -135,6 +135,11 @@ libbitcoin_common_a_SOURCES = \
   version.cpp \
   $(BITCOIN_CORE_H)
 
+if GLIBC_BACK_COMPAT
+libbitcoin_common_a_SOURCES += compat/glibc_compat.cpp
+libbitcoin_common_a_SOURCES += compat/glibcxx_compat.cpp
+endif
+
 libbitcoin_cli_a_SOURCES = \
   rpcclient.cpp \
   $(BITCOIN_CORE_H)