Quiet ar with ARFLAGS rather than > null & Remove CC ?= cc

`CC`, `AR` and `ARFLAGS` are all implicit variables in GNU `make` (the `README` _specifies GNU_ `make`).
`CC` and `AR` already defaulted appropriately (and turns out, `CC ?=` doesn’t overwrite the default).
`ARFLAGS` defaulted verbose, so un-verbose-fy it is the more direct *and platform-agnostic* way to quiet `ar`.

Makefile

@@ -12,7 +12,7 @@ SOEXT ?= $(shell ruby -e 'puts RbConfig::CONFIG["SOEXT"]')
 
 CPPFLAGS := -Iinclude $(CPPFLAGS)
 CFLAGS := -g -O2 -std=c99 -Wall -Werror -Wextra -Wpedantic -Wundef -Wconversion -Wno-missing-braces -fPIC -fvisibility=hidden $(CFLAGS)
-CC ?= cc
+ARFLAGS := -r
 WASI_SDK_PATH := /opt/wasi-sdk
 
 MAKEDIRS ?= mkdir -p
@@ -36,7 +36,7 @@ build/libprism.$(SOEXT): $(SHARED_OBJECTS)
 
 build/libprism.a: $(STATIC_OBJECTS)
 	$(ECHO) "building $@"
-	$(Q) $(AR) $(ARFLAGS) $@ $(STATIC_OBJECTS) $(Q1:0=>/dev/null)
+	$(Q) $(AR) $(ARFLAGS) $@ $(STATIC_OBJECTS)
 
 javascript/src/prism.wasm: Makefile $(SOURCES) $(HEADERS)
 	$(ECHO) "building $@"