buildsys: automatically select correct PKG_CONFIG_PATH on Solaris

For 32-bit builds, make sure that, if /usr/lib/amd64/pkgconfig is in the
path, we put /usr/lib/pkgconfig before it, so that we find the .pc files
for 32-bit versions of packages.

For 64-bit builds, make sure that, if /usr/lib/pkgconfig is in the path,
we put /usr/lib/amd64/pkgconfig before it and, if it's not in the path,
we have /usr/lib/amd64/pkgconfig at the end of the path, so that we find
the .pc files for 64-bit versions of packages.

Original patch by Guy Harris <gharris@sonic.net>.

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>

configure.ac

@@ -373,6 +373,61 @@ aux*)
     ;;
 esac
 
+# Solaris pkg-config is annoying.  For at least one package (D-Bus, I'm
+# looking at *you*!), there are separate include files for 32-bit and
+# 64-bit builds (I guess using "unsigned long long" as a 64-bit integer
+# type on a 64-bit build is like crossing the beams or something), and
+# there are two separate .pc files, so if we're doing a 32-bit build we
+# should make sure we look in /usr/lib/pkgconfig for .pc files and if
+# we're doing a 64-bit build we should make sure we look in
+# /usr/lib/amd64/pkgconfig for .pc files.
+#
+case "$host_os" in
+solaris*)
+    if test "$ac_cv_sizeof_void_p" -eq 8; then
+        #
+        # 64-bit build.  If the path is empty, set it to
+        # /usr/lib/amd64/pkgconfig; otherwise, if
+        # /usr/lib/pkgconfig appears in the path, prepend
+        # /usr/lib/amd64/pkgconfig to it; otherwise, put
+        # /usr/lib/amd64/pkgconfig at the end.
+        #
+        if test -z "$PKG_CONFIG_PATH"; then
+            #
+            # Not set, or empty.  Set it to
+            # /usr/lib/amd64/pkgconfig.
+            #
+            PKG_CONFIG_PATH=/usr/lib/amd64/pkgconfig
+        elif test ! -z `echo "$PKG_CONFIG_PATH" | grep "/usr/lib/pkgconfig`; then
+            #
+            # It contains /usr/lib/pkgconfig.  Prepend
+            # /usr/lib/amd64/pkgconfig to /usr/lib/pkgconfig.
+            #
+            PKG_CONFIG_PATH=`echo "$PKG_CONFIG_PATH" | sed "s;/usr/lib/pkgconfig;/usr/lib/amd64/pkgconfig:/usr/lib/pkgconfig;"`
+        else
+            #
+            # Not empty, but doesn't contain /usr/lib/pkgconfig.
+            # Append /usr/lib/amd64/pkgconfig to it.
+            #
+            PKG_CONFIG_PATH="$PKG_CONFIG_PATH:/usr/lib/amd64/pkgconfig"
+        fi
+        export PKG_CONFIG_PATH
+    elif test "$ac_cv_sizeof_void_p" -eq 4; then
+        #
+        # 32-bit build.  If /usr/amd64/lib/pkgconfig appears
+        # in the path, prepend /usr/lib/pkgconfig to it.
+        #
+        if test ! -z `echo "$PKG_CONFIG_PATH" | grep "/usr/lib/amd64/pkgconfig`; then
+            #
+            # It contains /usr/lib/amd64/pkgconfig.  Prepend
+            # /usr/lib/pkgconfig to /usr/lib/amd64/pkgconfig.
+            #
+            PKG_CONFIG_PATH=`echo "$PKG_CONFIG_PATH" | sed "s;/usr/lib/amd64/pkgconfig;/usr/lib/pkgconfig:/usr/lib/amd64/pkgconfig;"`
+            export PKG_CONFIG_PATH
+        fi
+    fi
+esac
+
 dnl If running under AIX, AC_AIX does not tell us that
 AC_MSG_CHECKING([for AIX defines])
 AC_EGREP_CPP([yes],