More M4 links

Author: j-woz

lb/code/m4/README.adoc

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+These may be hard links to swift-t/dev/m4/*.m4

lb/code/m4/syslibs.m4

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+
+# SYSLIBS.M4
+
+# We take system libraries out of arguments to the linker
+# to prevent system libraries from pre-empting custom user
+# library locations.
+# We do not currently have a solution for this on the Mac. (#88)
+# Cf. https://code.google.com/p/exm-issues/issues/detail?id=546
+
+AC_MSG_NOTICE([Generating system-libs.txt])
+
+AC_PATH_PROG([LDCONFIG],[ldconfig],[no],["$PATH:/sbin"])
+if [[ ${LDCONFIG} == no ]]
+then
+    AC_MSG_NOTICE([\
+Could not find ldconfig. \
+The linker may use system directories. \
+See /dev/m4/syslib.m4 for more information.])
+fi
+
+if [[ ${USE_MAC} == "no" ]]
+then
+    # This does not work on the Mac
+    ${LDCONFIG} -v 2>/dev/null | grep -vP '\t' | cut -d : -f 1 > system-libs.txt
+else
+     touch system-libs.txt
+fi

turbine/code/m4/README.adoc

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+These may be hard links to swift-t/dev/m4/*.m4