If you configure with the various --with-alsa options, the resulting include and/or lib directories are not passed down into the build. I had to hack up the CompileNativeLibraries.gmk file in order to finish a build.

diff -r bd437f34c7bc makefiles/CompileNativeLibraries.gmk
--- a/makefiles/CompileNativeLibraries.gmk Fri Apr 26 18:21:31 2013
+0200
+++ b/makefiles/CompileNativeLibraries.gmk Tue May 07 12:06:43 2013
-0400
@@ -2874,7 +2874,7 @@
                  PLATFORM_API_LinuxOS_ALSA_Ports.c,\
          LANG:=C,\
          OPTIMIZATION:=LOW, \
- CFLAGS:=$(CFLAGS_JDKLIB) \
+ CFLAGS:=-I/export/users/bpittore/tools/alsa-ppc/include
$(CFLAGS_JDKLIB) \
              $(LIBJSOUND_CFLAGS) \
              -DUSE_DAUDIO=TRUE \
              -DUSE_PORTS=TRUE \
@@ -2883,7 +2883,7 @@
MAPFILE:=$(JDK_TOPDIR)/makefiles/mapfiles/libjsoundalsa/mapfile-vers, \
          LDFLAGS:=$(LDFLAGS_JDKLIB)\
               $(call SET_SHARED_LIBRARY_ORIGIN),\
- LDFLAGS_SUFFIX:=-lasound -ljava -ljvm,\
+ LDFLAGS_SUFFIX:=-L/export/users/bpittore/tools/alsa-ppc/lib -lasound
-ljava -ljvm,\
          OBJECT_DIR:=$(JDK_OUTPUTDIR)/objs/libjsoundalsa))

  $(BUILD_LIBJSOUNDALSA) : $(BUILD_LIBJAVA)