Always allocate linear memory using mmap (#3052)

With this approach we can omit using memset() for the newly allocated memory
therefore the physical pages are not being used unless touched by the program.

This also simplifies the implementation.

product-mini/platforms/linux-sgx/CMakeLists.txt

@@ -176,3 +176,10 @@ else()
         OUTPUT_VARIABLE cmdOutput
     )
 endif()
+
+if (WAMR_BUILD_SPEC_TEST EQUAL 1)
+    execute_process(
+        COMMAND bash -c "sed -i -E 's/<ReservedMemMaxSize>0x1000000<\\/ReservedMemMaxSize>/<ReservedMemMaxSize>0x8000000<\\/ReservedMemMaxSize>/g' ${CMAKE_CURRENT_SOURCE_DIR}/enclave-sample/Enclave/Enclave.config.xml"
+        OUTPUT_VARIABLE cmdOutput
+    )
+endif()

product-mini/platforms/nuttx/wamr.mk

@@ -391,6 +391,7 @@ CSRCS += nuttx_platform.c \
          posix_thread.c \
          posix_time.c \
          posix_sleep.c \
+         mremap.c \
          mem_alloc.c \
          ems_kfc.c \
          ems_alloc.c \
@@ -401,6 +402,7 @@ CSRCS += nuttx_platform.c \
          bh_hashmap.c \
          bh_list.c \
          bh_log.c \
+         bh_memutils.c \
          bh_queue.c \
          bh_vector.c \
          bh_read_file.c \
@@ -416,6 +418,7 @@ CSRCS += nuttx_platform.c \
 ASRCS += $(INVOKE_NATIVE)
 
 VPATH += $(SHARED_ROOT)/platform/nuttx
+VPATH += $(SHARED_ROOT)/platform/common/memory
 VPATH += $(SHARED_ROOT)/platform/common/posix
 VPATH += $(SHARED_ROOT)/platform/common/libc-util
 VPATH += $(SHARED_ROOT)/mem-alloc