Establish Stack Frame insider CallEHFunclet

This commit revises the implementation of CallEHFunclet to establish
stack frame appropriately.

This commit allows libunwind to work correctly for the frame created by
CallEHFunclet.

This revises the PR suggested by #4581, which fixes #4579

Edited-by: MyungJoo Ham <myungjoo.ham@samsung.com>

src/vm/arm/ehhelpers.S

@@ -47,6 +47,8 @@ OFFSET_OF_FRAME=(4 + SIZEOF__GSCookie)
         //
         // Runtime check for 8-byte alignment. 
         PROLOG_STACK_SAVE r7
+        // We lose stack unwindability here by configuring fp(r7) incorrectely
+        // here.
         and r0, r7, #4
         sub sp, sp, r0
 
@@ -99,6 +101,7 @@ OFFSET_OF_FRAME=(4 + SIZEOF__GSCookie)
         NESTED_ENTRY CallEHFunclet, _TEXT, NoHandler
 
         PROLOG_PUSH  "{r4-r11, lr}"
+        PROLOG_STACK_SAVE_OFFSET  r7, #12
         alloc_stack  4
 
         // On entry:
@@ -124,7 +127,8 @@ OFFSET_OF_FRAME=(4 + SIZEOF__GSCookie)
         // frame pointer for accessing the locals in the parent method.
         NESTED_ENTRY CallEHFilterFunclet, _TEXT, NoHandler
 
-        PROLOG_PUSH  "{lr}"
+        PROLOG_PUSH  "{r7, lr}"
+        PROLOG_STACK_SAVE r7
         alloc_stack  4
 
         // On entry:
@@ -140,6 +144,6 @@ OFFSET_OF_FRAME=(4 + SIZEOF__GSCookie)
         blx r2
 
         free_stack   4
-        EPILOG_POP   "{pc}"
+        EPILOG_POP   "{r7, pc}"
 
         NESTED_END CallEHFilterFunclet, _TEXT