Clean up global variables namespace, save a few 100 bytes of flash (#5368)

* reduce scope of some variables to "static"

these are not used anywhere else. Making them static avoid name conflicts, cleans up the global scope and in some cases allows for better  optimization by the compiler.

* remove unused reference ``tz``from analog clock usermod

* side-catch: remove two "local var shadows global var" warnings

* reduce scope of functions declared globally, but not used anywhere else
Safe to make static
* declared in fcn_declare.h, only used locally in one file
* not declared in fcn_declare.h, only used locally

* HUB75 small optimization
make bit array functions "static inline"
-> better for optimization, saves some bytes because the compiler does not need to preserve a non-inline function copy for external references.

* a few more static functions
as suggested by the rabbit.

wled00/ntp.cpp

@@ -2,6 +2,11 @@
 #include "wled.h"
 #include "fcn_declare.h"
 
+// forward declarations
+static void sendNTPPacket();
+static bool checkNTPResponse();
+
+
 // WARNING: may cause errors in sunset calculations on ESP8266, see #3400
 // building with `-D WLED_USE_REAL_MATH` will prevent those errors at the expense of flash and RAM
 
@@ -11,7 +16,7 @@
 //#define WLED_DEBUG_NTP
 #define NTP_SYNC_INTERVAL 42000UL //Get fresh NTP time about twice per day
 
-Timezone* tz;
+static Timezone* tz;
 
 #define TZ_UTC                  0
 #define TZ_UK                   1
@@ -42,7 +47,7 @@ Timezone* tz;
 #define TZ_COUNT               25
 #define TZ_INIT               255
 
-byte tzCurrent = TZ_INIT; //uninitialized
+static byte tzCurrent = TZ_INIT; //uninitialized
 
 /* C++11 form -- static std::array<std::pair<TimeChangeRule, TimeChangeRule>, TZ_COUNT> TZ_TABLE PROGMEM = {{ */
 static const std::pair<TimeChangeRule, TimeChangeRule> TZ_TABLE[] PROGMEM = {
@@ -199,7 +204,7 @@ void handleNetworkTime()
   }
 }
 
-void sendNTPPacket()
+static void sendNTPPacket()
 {
   if (!ntpServerIP.fromString(ntpServerName)) //see if server is IP or domain
   {
@@ -245,7 +250,7 @@ static bool isValidNtpResponse(const byte* ntpPacket) {
   return true;
 }
 
-bool checkNTPResponse()
+static bool checkNTPResponse()
 {
   int cb = ntpUdp.parsePacket();
   if (cb < NTP_MIN_PACKET_SIZE) {