Remove explict use of ASCII encoding

Replace the use of CFStringGetCString with kCFStringEncodingASCII specified
with CFStringGetFileSystemRepresentation which will ensure the correct
character encoding is used to conver the CFString into a NULL terminated
char array suitable for use with POSIX APIs.

(cherry picked from commit 2a4b5f9e)

Change-Id: Ie6e2027e59b49ca634c7308bcda7bb492d372f46

adb/get_my_path_darwin.c

@@ -24,7 +24,7 @@ void get_my_path(char *s, size_t maxLen)
     CFStringRef executablePathString = CFURLCopyFileSystemPath(executableURL, kCFURLPOSIXPathStyle);
     CFRelease(executableURL);
 
-    CFStringGetCString(executablePathString, s, maxLen, kCFStringEncodingASCII);
+    CFStringGetFileSystemRepresentation(executablePathString, s, maxLen);
     CFRelease(executablePathString);
 }
 

fastboot/util_osx.c

@@ -36,7 +36,7 @@ void get_my_path(char s[PATH_MAX])
     CFStringRef executablePathString = CFURLCopyFileSystemPath(executableURL, kCFURLPOSIXPathStyle);
     CFRelease(executableURL);
 
-    CFStringGetCString(executablePathString, s, PATH_MAX-1, kCFStringEncodingASCII);
+    CFStringGetFileSystemRepresentation(executablePathString, s, PATH_MAX-1);
     CFRelease(executablePathString);
 
 	char *x;