Disable Werror when building perf

This replaces extra flags used to disable speciffic warnings being treated as errors.
Related python#9

PKGBUILD

@@ -89,7 +89,7 @@ build() {
     prefix=/usr \
     lib=lib/perf \
     perfexecdir=lib/perf \
-    EXTRA_CFLAGS=' -Wno-error=bad-function-cast -Wno-error=declaration-after-statement -Wno-error=switch-enum' \
+    WERROR=0 \
     NO_SDT=1 \
     BUILD_BPF_SKEL=1 \
     PYTHON=python \