doc: add build requirement in some crypto PMD guides

The following crypto PMDs use the Intel Multi-buffer library:
- AESNI MB PMD
- AESNI GCM PMD
- ZUC PMD
- KASUMI PMD
- SNOW3G PMD

When this library is built with gcc < 5.0, it might throw
some compilation issues. A workaround has been added in the
repo of this library, so a note on this has been added
to the documentation of these PMDs.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>

doc/guides/cryptodevs/aesni_gcm.rst

@@ -50,6 +50,13 @@ can be downloaded in `<https://github.com/01org/intel-ipsec-mb/archive/v0.53.zip
     make
     make install
 
+.. note::
+
+   Compilation of the Multi-Buffer library is broken when GCC < 5.0, if library <= v0.53.
+   If a lower GCC version than 5.0, the workaround proposed by the following link
+   should be used: `<https://github.com/intel/intel-ipsec-mb/issues/40>`_.
+
+
 As a reference, the following table shows a mapping between the past DPDK versions
 and the external crypto libraries supported by them:
 

doc/guides/cryptodevs/aesni_mb.rst

@@ -72,6 +72,12 @@ can be downloaded from `<https://github.com/01org/intel-ipsec-mb/archive/v0.53.z
     make
     make install
 
+.. note::
+
+   Compilation of the Multi-Buffer library is broken when GCC < 5.0, if library <= v0.53.
+   If a lower GCC version than 5.0, the workaround proposed by the following link
+   should be used: `<https://github.com/intel/intel-ipsec-mb/issues/40>`_.
+
 As a reference, the following table shows a mapping between the past DPDK versions
 and the Multi-Buffer library version supported by them:
 

doc/guides/cryptodevs/kasumi.rst

@@ -47,6 +47,12 @@ on their system before building DPDK:
     make
     make install
 
+.. note::
+
+   Compilation of the Multi-Buffer library is broken when GCC < 5.0, if library <= v0.53.
+   If a lower GCC version than 5.0, the workaround proposed by the following link
+   should be used: `<https://github.com/intel/intel-ipsec-mb/issues/40>`_.
+
 As a reference, the following table shows a mapping between the past DPDK versions
 and the external crypto libraries supported by them:
 

doc/guides/cryptodevs/snow3g.rst

@@ -46,6 +46,12 @@ on their system before building DPDK:
     make
     make install
 
+.. note::
+
+   Compilation of the Multi-Buffer library is broken when GCC < 5.0, if library <= v0.53.
+   If a lower GCC version than 5.0, the workaround proposed by the following link
+   should be used: `<https://github.com/intel/intel-ipsec-mb/issues/40>`_.
+
 As a reference, the following table shows a mapping between the past DPDK versions
 and the external crypto libraries supported by them:
 

doc/guides/cryptodevs/zuc.rst

@@ -46,6 +46,12 @@ on their system before building DPDK:
     make
     make install
 
+.. note::
+
+   Compilation of the Multi-Buffer library is broken when GCC < 5.0, if library <= v0.53.
+   If a lower GCC version than 5.0, the workaround proposed by the following link
+   should be used: `<https://github.com/intel/intel-ipsec-mb/issues/40>`_.
+
 As a reference, the following table shows a mapping between the past DPDK versions
 and the external crypto libraries supported by them: