Fix iOS profiling symbols (#2085)

* Always generate dsym for iOS builds

Fixes issue where Instruments fails to find symbols for profiler

* Remove docs for fixing missing symbols in Instruments

platforms/ios/DEVELOPING.md

@@ -40,19 +40,3 @@ set_target_properties(myIosTarget PROPERTIES XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT
 ```
 
 Some build configurations are more easily applied through Xcode settings, and some are only relevant when Xcode is the target IDE.
-
-## Fix missing symbols when profiling in Instruments ##
-
-After running the Time Profiler in Xcode's Instruments you might see traces with memory addresses instead of function names, like in the image below:
-
-![Instruments trace with missing symbols](/images/instruments-missing-symbols.png)
-
-For each Instruments run where function names are missing use the following steps to locate the symbols that Instruments needs to show the names correctly.
-
-After collecting data from a run and stopping the Time Profiler, go to `File` > `Symbols...`
-
-In the symbols pane that appears, select `TangramMap` in the menu on the left and then press the folder icon next to the binary path to choose the correct binary file.
-
-![Instruments symbols pane](/images/instruments-locate-binary.png)
-
-The correct binary file is the file named `TangramMap` in the directory shown in the file chooser that appears (located within the tangram-es repository at `build/ios/Release-iphoneos/TangramMap.framework/TangramMap`).  After choosing the binary file, press `Done` to close the symbols pane and the function names will appear correctly in your Time Profiler trace.

platforms/ios/config.cmake

@@ -105,6 +105,8 @@ set_target_properties(TangramMap PROPERTIES
   XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++14"
   XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++"
   XCODE_ATTRIBUTE_GCC_TREAT_WARNINGS_AS_ERRORS "YES"
+  # Generate dsym for all build types to ensure symbols are available in profiling.
+  XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS "YES"
 )
 
 ### Configure static library build target.
@@ -169,6 +171,8 @@ set_target_properties(tangram-static PROPERTIES
   XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++14"
   XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++"
   XCODE_ATTRIBUTE_GCC_TREAT_WARNINGS_AS_ERRORS "YES"
+  # Generate dsym for all build types to ensure symbols are available in profiling.
+  XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS "YES"
   # The Xcode settings below are to pre-link our static libraries into a single
   # archive. Xcode will take the objects from this target and from all of the
   # pre-link libraries, combine them, and resolve the symbols into one "master"