fix(Build): Added OS detection to gcc.mk (#1321)

Libraries/CMSIS/Device/Maxim/GCC/gcc.mk

@@ -106,6 +106,59 @@ OBJS        += $(PROJ_OBJS)
 
 ################################################################################
 # Goals
+################################################################################
+# Get the operating system name.  If this is Cygwin, the .d files will be
+# munged to convert c: into /cygdrive/c so that "make" will be happy with the
+# auto-generated dependencies. Also if this is Cygwin, file paths for ARM GCC
+# will be converted from /cygdrive/c to C:.
+################################################################################
+
+# Detect target OS
+# windows : native windows
+# windows_msys : MSYS2 on windows
+# windows_cygwin : Cygwin on windows (legacy config from old sdk)
+# linux : Any linux distro
+# macos : MacOS
+ifeq "$(_OS)" ""
+
+ifeq "$(OS)" "Windows_NT"
+_OS = windows
+
+UNAME_RESULT := $(shell uname -s 2>&1)
+# MSYS2 may be present on Windows.  In this case,
+# linux utilities should be used.  However, the OS environment
+# variable will still be set to Windows_NT since we configure
+# MSYS2 to inherit from Windows by default.
+# Here we'll attempt to call uname (only present on MSYS2)
+# while routing stderr -> stdout to avoid throwing an error
+# if uname can't be found.
+ifneq ($(findstring CYGWIN, $(UNAME_RESULT)), )
+CYGWIN=True
+_OS = windows_cygwin
+endif
+
+ifneq ($(findstring MSYS, $(UNAME_RESULT)), )
+MSYS=True
+_OS = windows_msys
+endif
+ifneq ($(findstring MINGW, $(UNAME_RESULT)), )
+MSYS=True
+_OS = windows_msys
+endif
+
+else # OS
+$(info "")
+UNAME_RESULT := $(shell uname -s)
+ifeq "$(UNAME_RESULT)" "Linux"
+_OS = linux
+endif
+ifeq "$(UNAME_RESULT)" "Darwin"
+_OS = macos
+endif
+
+endif
+
+endif
 
 # The default goal, which causes the example to be built.
 .DEFAULT_GOAL :=