Fix arm64 signed char (#1006)

Author: rolandreichweinbmw

test/test_bit_stream.cpp

@@ -1075,4 +1075,4 @@ namespace
   };
 }
 
-#include "etl/private/diagnostic_pop.h"
+#include "etl/private/diagnostic_pop.h"

test/test_bit_stream_reader_little_endian.cpp

@@ -215,7 +215,7 @@ namespace
     TEST(test_read_int8_t)
     {
       std::array<char, 4U> storage  = { char(0x80), char(0x5A), char(0xA5), char(0xFF) };
-      std::array<char, 4U> expected = { int8_t(0x01), int8_t(0x5A), int8_t(0xA5), int8_t(0xFF) };
+      std::array<signed char, 4U> expected = { int8_t(0x01), int8_t(0x5A), int8_t(0xA5), int8_t(0xFF) };
 
       etl::bit_stream_reader bit_stream(storage.data(), storage.size(), etl::endian::little);
 

test/test_correlation.cpp

@@ -86,7 +86,7 @@ namespace
     //*************************************************************************
     TEST(test_char_correlation_default_constructor)
     {
-      etl::correlation<etl::correlation_type::Population, char, int32_t> correlation;
+      etl::correlation<etl::correlation_type::Population, signed char, int32_t> correlation;
 
       double correlation_result = correlation;
 

test/test_covariance.cpp

@@ -86,7 +86,7 @@ namespace
     //*************************************************************************
     TEST(test_char_covariance_default_constructor)
     {
-      etl::covariance<etl::covariance_type::Population, char, int32_t> covariance;
+      etl::covariance<etl::covariance_type::Population, signed char, int32_t> covariance;
 
       double covariance_result = covariance;