define new APP_CC configuration variable for building apps/demos/tests

For Cell, need to use different compilers for the libraries vs. the demos/tests
to avoid strange link error regarding "_Unwind_GetIPInfo@GCC_4.2.0"
diff --git a/configs/default b/configs/default
index cd2c39c..94582d8 100644
--- a/configs/default
+++ b/configs/default
@@ -23,6 +23,10 @@
 CXXFLAGS = -O
 GLU_CFLAGS = 
 
+# Compiler for building demos/tests/etc
+APP_CC = $(CC)
+APP_CXX = $(CXX)
+
 # Misc tools and flags
 MKLIB_OPTIONS = 
 MKDEP = makedepend
diff --git a/configs/linux-cell b/configs/linux-cell
index cdaa17c..86651b8 100644
--- a/configs/linux-cell
+++ b/configs/linux-cell
@@ -12,6 +12,8 @@
 CC = ppu32-gcc
 CXX = ppu32-g++
 HOST_CC = gcc
+APP_CC = gcc
+APP_CXX = g++
 
 OPT_FLAGS = -O3
 
@@ -19,7 +21,7 @@
 ## For SDK 2.1: (plus, remove -DSPU_MAIN_PARAM_LONG_LONG below)
 #SDK = /opt/ibm/cell-sdk/prototype/sysroot/usr
 ## For SDK 3.0:
-SDK = /opt/cell/sdk/usr/
+SDK = /opt/cell/sdk/usr
 
 
 CFLAGS = $(OPT_FLAGS) -Wall -Winline -fPIC -m32 -mabi=altivec -maltivec \