Disable -Werror to avoid build errors on user machines with untested compilers.

It was already an aggressive default, but no longer makes
sense due to lack of persistent project maintenance.

(Causing only pain for users uninterested in debugging warnings)

llvm-svn: 208100
diff --git a/poolalloc/Makefile.common.in b/poolalloc/Makefile.common.in
index 20e8d65..c57bf03 100644
--- a/poolalloc/Makefile.common.in
+++ b/poolalloc/Makefile.common.in
@@ -19,7 +19,7 @@
 # Set the root directory of this project's install prefix
 PROJ_INSTALL_ROOT := @prefix@
 
-CXXFLAGS += -Werror -Wall -Wno-deprecated
+CXXFLAGS += -Wall -Wno-deprecated
 
 #
 # Paths to various utilities