fix build with very old gcc (#4048)

* clear bom marker, avoid vector data function

benchmark/benchncnn.cpp

-// Tencent is pleased to support the open source community by making ncnn available.
+// Tencent is pleased to support the open source community by making ncnn available.
 //
 // Copyright (C) 2018 THL A29 Limited, a Tencent company. All rights reserved.
 //

src/c_api.cpp

@@ -832,7 +832,7 @@ public:
             bottom_blobs0[i] = (ncnn_mat_t)&bottom_blobs[i];
         }
         std::vector<ncnn_mat_t> top_blobs0(n2, (ncnn_mat_t)0);
-        int ret = layer->forward_n(layer, bottom_blobs0.data(), n, top_blobs0.data(), n2, (ncnn_option_t)&opt);
+        int ret = layer->forward_n(layer, &bottom_blobs0[0], n, &top_blobs0[0], n2, (ncnn_option_t)&opt);
         for (int i = 0; i < n2; i++)
         {
             top_blobs[i] = *(Mat*)top_blobs0[i];
@@ -858,7 +858,7 @@ public:
         {
             bottom_top_blobs0[i] = (ncnn_mat_t)&bottom_top_blobs[i];
         }
-        return layer->forward_inplace_n(layer, bottom_top_blobs0.data(), n, (ncnn_option_t)&opt);
+        return layer->forward_inplace_n(layer, &bottom_top_blobs0[0], n, (ncnn_option_t)&opt);
     }
 
     virtual int forward_inplace(Mat& bottom_top_blob, const Option& opt) const

src/layer/roialign.cpp

-// Tencent is pleased to support the open source community by making ncnn available.
+// Tencent is pleased to support the open source community by making ncnn available.
 //
 // Copyright (C) 2018 THL A29 Limited, a Tencent company. All rights reserved.
 //

src/layer/x86/roialign_x86.cpp

-// Tencent is pleased to support the open source community by making ncnn available.
+// Tencent is pleased to support the open source community by making ncnn available.
 //
 // Copyright (C) 2020 THL A29 Limited, a Tencent company. All rights reserved.
 //

src/mat_pixel_affine.cpp

-// Tencent is pleased to support the open source community by making ncnn available.
+// Tencent is pleased to support the open source community by making ncnn available.
 //
 // Copyright (C) 2020 THL A29 Limited, a Tencent company. All rights reserved.
 //

src/modelbin.cpp

@@ -121,14 +121,14 @@ Mat ModelBinFromDataReader::load(int w, int type) const
             {
                 std::vector<unsigned short> float16_weights;
                 float16_weights.resize(align_data_size);
-                nread = d->dr.read(float16_weights.data(), align_data_size);
+                nread = d->dr.read(&float16_weights[0], align_data_size);
                 if (nread != align_data_size)
                 {
                     NCNN_LOGE("ModelBin read float16_weights failed %zd", nread);
                     return Mat();
                 }
 
-                m = Mat::from_float16(float16_weights.data(), w);
+                m = Mat::from_float16(&float16_weights[0], w);
             }
 
             return m;
@@ -149,7 +149,7 @@ Mat ModelBinFromDataReader::load(int w, int type) const
             {
                 std::vector<signed char> int8_weights;
                 int8_weights.resize(align_data_size);
-                nread = d->dr.read(int8_weights.data(), align_data_size);
+                nread = d->dr.read(&int8_weights[0], align_data_size);
                 if (nread != align_data_size)
                 {
                     NCNN_LOGE("ModelBin read int8_weights failed %zd", nread);
@@ -160,7 +160,7 @@ Mat ModelBinFromDataReader::load(int w, int type) const
                 if (m.empty())
                     return m;
 
-                memcpy(m.data, int8_weights.data(), w);
+                memcpy(m.data, &int8_weights[0], w);
             }
 
             return m;
@@ -210,7 +210,7 @@ Mat ModelBinFromDataReader::load(int w, int type) const
             size_t align_weight_data_size = alignSize(w * sizeof(unsigned char), 4);
             std::vector<unsigned char> index_array;
             index_array.resize(align_weight_data_size);
-            nread = d->dr.read(index_array.data(), align_weight_data_size);
+            nread = d->dr.read(&index_array[0], align_weight_data_size);
             if (nread != align_weight_data_size)
             {
                 NCNN_LOGE("ModelBin read index_array failed %zd", nread);

tools/plugin/ImageWatchNCNN.natvis

-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
   <UIVisualizer ServiceId="{A452AFEA-3DF6-46BB-9177-C0B08F318025}" Id="1" MenuName="Add to Image Watch"/>
 

tools/plugin/ImageWatchNNIE.natvis

-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
   <UIVisualizer ServiceId="{A452AFEA-3DF6-46BB-9177-C0B08F318025}" Id="1" MenuName="Add to Image Watch"/>