Add "nano.specs" for ARM linker

Author: valeros

platformio/builder/scripts/basearm.py

@@ -45,9 +45,10 @@
 
     LINKFLAGS=[
         "-Os",
-        "-Wl,--gc-sections",
+        "-Wl,--gc-sections,--relax",
         "-mthumb",
-        "-mcpu=${BOARD_OPTIONS['build']['cpu']}"
+        "-mcpu=${BOARD_OPTIONS['build']['cpu']}",
+        "--specs=nano.specs"
     ],
 
     LIBS=["c", "gcc", "m"],

platformio/builder/scripts/baseavr.py

@@ -44,7 +44,7 @@
     LINKFLAGS=[
         "-Os",
         "-mmcu=$BOARD_MCU",
-        "-Wl,--gc-sections"
+        "-Wl,--gc-sections,--relax"
     ],
 
     LIBS=["m"],

platformio/builder/scripts/teensy.py

@@ -16,6 +16,9 @@
     SConscript(env.subst(join("$PIOBUILDER_DIR", "scripts", "baseavr.py")))
 elif env.get("BOARD_OPTIONS", {}).get("build", {}).get("core") == "teensy3":
     SConscript(env.subst(join("$PIOBUILDER_DIR", "scripts", "basearm.py")))
+    env.Append(
+        LINKFLAGS=["-Wl,--defsym=__rtc_localtime=$UNIX_TIME"]
+    )
 
 env.Append(
     CPPDEFINES=[
@@ -26,14 +29,7 @@
     CXXFLAGS=[
         "-std=gnu++0x",
         "-felide-constructors"
-    ],
-
-    LINKFLAGS=[
-        "-Wl,--gc-sections,--relax,--defsym=__rtc_localtime=$UNIX_TIME",
-        "--specs=nano.specs"
-    ],
-
-    LIBS=["m"]
+    ]
 )
 
 if isfile(env.subst(join(