RFR: JDK-8075495: Update jtreg bin location in configure

[Erik Joelsson]

Jtreg removed the platform specific bin directories. Configure still 
picks up the jtreg launcher from win32/bin. This needs to be fixed. This 
patch is for jdk9. The same patch applies to jdk8u-dev and I would like 
to fix it there too.

Bug: https://bugs.openjdk.java.net/browse/JDK-8075495
Patch:
diff -r 3d44432e07d3 common/autoconf/toolchain.m4
--- a/common/autoconf/toolchain.m4
+++ b/common/autoconf/toolchain.m4
@@ -763,7 +763,7 @@
        BASIC_FIXUP_PATH([JT_HOME])

        # jtreg win32 script works for everybody
-      JTREGEXE="$JT_HOME/win32/bin/jtreg"
+      JTREGEXE="$JT_HOME/bin/jtreg"

        if test ! -f "$JTREGEXE"; then
          AC_MSG_ERROR([JTReg executable does not exist: $JTREGEXE])

/Erik