Add support for --enable-oe-sdk

This commit enables running GTEST cases via make check

Change-Id: I4b74b9f9bde41f970fc2b1b388a888c7fb629bdd
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>
diff --git a/configure.ac b/configure.ac
index 7faec80..65942b6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -25,6 +25,27 @@
 PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus],, [AC_MSG_ERROR([Could not find sdbusplus...openbmc/sdbusplus package required])])
 PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces],, [AC_MSG_ERROR([Could not find phosphor-dbus-interfaces...openbmc/phosphor-dbus-interfaces package required])])
 
+# check/enable oe-sdk
+AX_PTHREAD([GTEST_CPPFLAGS="-DGTEST_HAS_PTHREAD=1"],[GTEST_CPPFLAGS="-DGTEST_HAS_PTHREAD=0"])
+AC_SUBST(GTEST_CPPFLAGS)
+AC_ARG_ENABLE([oe-sdk],
+    AS_HELP_STRING([--enable-oe-sdk], [Link testcases absolutely against OE SDK so they can be ran within it.])
+)
+AC_ARG_VAR(OECORE_TARGET_SYSROOT,
+    [Path to the OE SDK SYSROOT])
+AS_IF([test "x$enable_oe_sdk" == "xyes"],
+    AS_IF([test "x$OECORE_TARGET_SYSROOT" == "x"],
+          AC_MSG_ERROR([OECORE_TARGET_SYSROOT must be set with --enable-oe-sdk])
+    )
+    AC_MSG_NOTICE([Enabling OE-SDK at $OECORE_TARGET_SYSROOT])
+    [
+        testcase_flags="-Wl,-rpath,\${OECORE_TARGET_SYSROOT}/lib"
+        testcase_flags="${testcase_flags} -Wl,-rpath,\${OECORE_TARGET_SYSROOT}/usr/lib"
+        testcase_flags="${testcase_flags} -Wl,-dynamic-linker,`find \${OECORE_TARGET_SYSROOT}/lib/ld-*.so | sort -r -n | head -n1`"
+    ]
+    AC_SUBST([OESDK_TESTCASE_FLAGS], [$testcase_flags])
+)
+
 # Check/set gtest specific functions.
 AS_IF([test "x$enable_tests" != "xno"], [
     PKG_CHECK_MODULES([GTEST], [gtest], [], [true])