Add source installation instructions for Centos 7 (iovisor#2248)

Add source installation instructions for Centos 7

INSTALL.md

@@ -14,6 +14,7 @@
  - [Ubuntu](#ubuntu---source)
  - [Fedora](#fedora---source)
  - [openSUSE](#opensuse---source)
+ - [Centos](#centos---source)
  - [Amazon Linux](#amazon-linux---source)
 * [Older Instructions](#older-instructions)
 
@@ -388,6 +389,55 @@ sudo make install
 popd
 ```
 
+## Centos - Source
+
+For Centos 7.6 only
+
+### Install build dependencies
+
+```
+sudo yum install -y epel-release
+sudo yum update -y
+sudo yum groupinstall -y "Development tools"
+sudo yum install -y elfutils-libelf-devel cmake3
+sudo yum install -y luajit luajit-devel # for Lua support
+```
+
+### Install and compile LLVM
+
+```
+curl -LO http:https://releases.llvm.org/7.0.1/llvm-7.0.1.src.tar.xz
+curl -LO http:https://releases.llvm.org/7.0.1/cfe-7.0.1.src.tar.xz
+tar -xf cfe-7.0.1.src.tar.xz
+tar -xf llvm-7.0.1.src.tar.xz
+
+mkdir clang-build
+mkdir llvm-build
+
+cd llvm-build
+cmake3 -G "Unix Makefiles" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \
+ -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr ../llvm-7.0.1.src
+make
+sudo make install
+
+cd ../clang-build
+cmake3 -G "Unix Makefiles" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \
+ -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr ../cfe-7.0.1.src
+make
+sudo make install
+cd ..
+```
+
+### Install and compile BCC
+
+```
+git clone https://github.com/iovisor/bcc.git
+mkdir bcc/build; cd bcc/build
+cmake .. -DCMAKE_INSTALL_PREFIX=/usr
+make
+sudo make install
+```
+
 ## Amazon Linux - Source
 
 Tested on Amazon Linux AMI release 2018.03 (kernel 4.14.47-56.37.amzn1.x86_64)