do not override compiler and do not strip

The default makefile sets the compiler to g++ or gcc. This leads to a wrong architecture when cross-compiling.
Remove the hardcoded compiler and just append the flags to CXX and CC.

Upstream-Status: Pending
Signed-off-by: Raphael Freudiger <raphael.freudiger@siemens.com>
Reviewed-By: Pascal Bach <pascal.bach@siemens.com>

Index: p7zip_9.20.1/makefile.machine
=====================================================================
--- p7zip_9.20.1/makefile.machine	2011-03-13 12:54:57.000000000 +0100
+++ p7zip_9.20.1/makefile.machine	2015-02-03 08:39:44.427696944 +0100
@@ -4,14 +4,14 @@
 
 OPTFLAGS=-O
 
-ALLFLAGS=${OPTFLAGS} -pipe -s \
+ALLFLAGS=${OPTFLAGS} -pipe \
     	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE \
 	-DNDEBUG -D_REENTRANT -DENV_UNIX \
 	-D_7ZIP_LARGE_PAGES \
 	$(LOCAL_FLAGS)
 
-CXX=g++ $(ALLFLAGS)
-CC=gcc $(ALLFLAGS)
+CXX+=$(ALLFLAGS)
+CC+=$(ALLFLAGS)
 CC_SHARED=-fPIC
 LINK_SHARED=-fPIC -shared