[arm][simulator] Fix tests build

test-sampler-api.cc calls {Simulator::get_pc} and
{Simulator::get_register}, hence these methods need to be exported.

R=ahaas@chromium.org

Change-Id: I5ba48d877f7101d1e8527c8138fa2e930ba686ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1611678Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61478}

src/arm/simulator-arm.h

@@ -96,7 +96,7 @@ class Simulator : public SimulatorBase {
   // architecture specification and is off by a 8 from the currently executing
   // instruction.
   void set_register(int reg, int32_t value);
-  int32_t get_register(int reg) const;
+  V8_EXPORT_PRIVATE int32_t get_register(int reg) const;
   double get_double_from_register_pair(int reg);
   void set_register_pair_from_double(int reg, double* value);
   void set_dw_register(int dreg, const int* dbl);
@@ -147,7 +147,7 @@ class Simulator : public SimulatorBase {
 
   // Special case of set_register and get_register to access the raw PC value.
   void set_pc(int32_t value);
-  int32_t get_pc() const;
+  V8_EXPORT_PRIVATE int32_t get_pc() const;
 
   Address get_sp() const { return static_cast<Address>(get_register(sp)); }