Allow old Make to build server. (ggerganov#2098)

Also make server build by default.

Tested with Make 3.82

Makefile

@@ -1,11 +1,5 @@
 # Define the default target now so that it is always the first target
-BUILD_TARGETS = main quantize quantize-stats perplexity embedding vdot train-text-from-scratch simple libembdinput.so embd-input-test
-
-ifdef LLAMA_BUILD_SERVER
- BUILD_TARGETS += server
- LLAMA_SERVER_VERBOSE ?= 1
-server: private CXXFLAGS += -DSERVER_VERBOSE=$(LLAMA_SERVER_VERBOSE)
-endif
+BUILD_TARGETS = main quantize quantize-stats perplexity embedding vdot train-text-from-scratch simple server libembdinput.so embd-input-test
 
 default: $(BUILD_TARGETS)
 
@@ -61,6 +55,10 @@ else
  CXXFLAGS += -DNDEBUG
 endif
 
+ifdef LLAMA_SERVER_VERBOSE
+ CXXFLAGS += -DSERVER_VERBOSE=$(LLAMA_SERVER_VERBOSE)
+endif
+
 # warnings
 CFLAGS += -Wall -Wextra -Wpedantic -Wcast-qual -Wdouble-promotion -Wshadow -Wstrict-prototypes -Wpointer-arith
 CXXFLAGS += -Wall -Wextra -Wpedantic -Wcast-qual -Wno-unused-function -Wno-multichar