Fix alignment issue in gpr_murmur_hash3
Fix alignment issue in gpr_murmur_hash3

This function cast a void* to a uint32_t*. This is invalid, since a uint32_t* must be 32-bit-aligned, while the input key clearly isn't. Even though the function later uses memcpy to access the memory, by that point the compiler is allowed to assume that the pointer is aligned, and so it can output code that does an unaligned memory access.

In practice, this resulted in a crash on some devices when this code is compiled with optimizations for 32-bit ARM with the Android NDK r14.

stanley-cheung/grpc,stanley-cheung/grpc,fuchsia-mirror/third_party-grpc,nicolasnoble/grpc,murgatroid99/grpc,kpayson64/grpc,ctiller/grpc,stanley-cheung/grpc,firebase/grpc,firebase/grpc,carl-mastrangelo/grpc,ejona86/grpc,ctiller/grpc,grpc/grpc,geffzhang/grpc,ctiller/grpc,geffzhang/grpc,jtattermusch/grpc,ctiller/grpc,ejona86/grpc,ctiller/grpc,thinkerou/grpc,jboeuf/grpc,grpc/grpc,thinkerou/grpc,pszemus/grpc,ncteisen/grpc,simonkuang/grpc,geffzhang/grpc,fuchsia-mirror/third_party-grpc,geffzhang/grpc,mehrdada/grpc,firebase/grpc,pszemus/grpc,murgatroid99/grpc,muxi/grpc,ncteisen/grpc,sreecha/grpc,geffzhang/grpc,mehrdada/grpc,grpc/grpc,fuchsia-mirror/third_party-grpc,ncteisen/grpc,dgquintas/grpc,PeterFaiman/ruby-grpc-minimal,pszemus/grpc,murgatroid99/grpc,mehrdada/grpc,thinkerou/grpc,grpc/grpc,jtattermusch/grpc,deepaklukose/grpc,kpayson64/grpc,donnadionne/grpc,ncteisen/grpc,pszemus/grpc,thinkerou/grpc,sreecha/grpc,murgatroid99/grpc,mehrdada/grpc,ncteisen/grpc,donnadionne/grpc,Vizerai/grpc,fuchsia-mirror/third_party-grpc,thinkerou/grpc,pszemus/grpc,jboeuf/grpc,ctiller/grpc,nicolasnoble/grpc,murgatroid99/grpc,carl-mastrangelo/grpc,chrisdunelm/grpc,deepaklukose/grpc,grpc/grpc,muxi/grpc,Vizerai/grpc,jtattermusch/grpc,grpc/grpc,Vizerai/grpc,simonkuang/grpc,chrisdunelm/grpc,stanley-cheung/grpc,deepaklukose/grpc,donnadionne/grpc,jboeuf/grpc,murgatroid99/grpc,chrisdunelm/grpc,jtattermusch/grpc,stanley-cheung/grpc,thinkerou/grpc,simonkuang/grpc,murgatroid99/grpc,kpayson64/grpc,sreecha/grpc,simonkuang/grpc,ncteisen/grpc,grpc/grpc,dgquintas/grpc,firebase/grpc,ncteisen/grpc,kpayson64/grpc,vjpai/grpc,fuchsia-mirror/third_party-grpc,sreecha/grpc,firebase/grpc,Vizerai/grpc,jboeuf/grpc,carl-mastrangelo/grpc,ctiller/grpc,kpayson64/grpc,dgquintas/grpc,carl-mastrangelo/grpc,thinkerou/grpc,grpc/grpc,grpc/grpc,PeterFaiman/ruby-grpc-minimal,stanley-cheung/grpc,Vizerai/grpc,pszemus/grpc,jboeuf/grpc,jtattermusch/grpc,Vizerai/grpc,muxi/grpc,dgquintas/grpc,jboeuf/grpc,thinkerou/grpc,kpayson64/grpc,murgatroid99/grpc,PeterFaiman/ruby-grpc-minimal,mehrdada/grpc,fuchsia-mirror/third_party-grpc,chrisdunelm/grpc,donnadionne/grpc,nicolasnoble/grpc,ejona86/grpc,muxi/grpc,mehrdada/grpc,vjpai/grpc,PeterFaiman/ruby-grpc-minimal,muxi/grpc,deepaklukose/grpc,muxi/grpc,vjpai/grpc,Vizerai/grpc,nicolasnoble/grpc,donnadionne/grpc,vjpai/grpc,sreecha/grpc,nicolasnoble/grpc,kpayson64/grpc,donnadionne/grpc,pszemus/grpc,stanley-cheung/grpc,chrisdunelm/grpc,sreecha/grpc,firebase/grpc,PeterFaiman/ruby-grpc-minimal,nicolasnoble/grpc,thinkerou/grpc,vjpai/grpc,carl-mastrangelo/grpc,geffzhang/grpc,geffzhang/grpc,ejona86/grpc,mehrdada/grpc,dgquintas/grpc,stanley-cheung/grpc,ncteisen/grpc,chrisdunelm/grpc,pszemus/grpc,donnadionne/grpc,ejona86/grpc,Vizerai/grpc,jtattermusch/grpc,firebase/grpc,kpayson64/grpc,ctiller/grpc,stanley-cheung/grpc,thinkerou/grpc,simonkuang/grpc,donnadionne/grpc,chrisdunelm/grpc,nicolasnoble/grpc,pszemus/grpc,ncteisen/grpc,ejona86/grpc,stanley-cheung/grpc,mehrdada/grpc,Vizerai/grpc,mehrdada/grpc,thinkerou/grpc,vjpai/grpc,muxi/grpc,simonkuang/grpc,jtattermusch/grpc,sreecha/grpc,ejona86/grpc,muxi/grpc,ctiller/grpc,donnadionne/grpc,ejona86/grpc,nicolasnoble/grpc,jboeuf/grpc,dgquintas/grpc,chrisdunelm/grpc,sreecha/grpc,grpc/grpc,carl-mastrangelo/grpc,dgquintas/grpc,fuchsia-mirror/third_party-grpc,sreecha/grpc,muxi/grpc,firebase/grpc,sreecha/grpc,jtattermusch/grpc,deepaklukose/grpc,Vizerai/grpc,chrisdunelm/grpc,carl-mastrangelo/grpc,stanley-cheung/grpc,jboeuf/grpc,firebase/grpc,mehrdada/grpc,ncteisen/grpc,geffzhang/grpc,vjpai/grpc,jboeuf/grpc,dgquintas/grpc,dgquintas/grpc,ejona86/grpc,carl-mastrangelo/grpc,jtattermusch/grpc,dgquintas/grpc,ctiller/grpc,sreecha/grpc,muxi/grpc,simonkuang/grpc,deepaklukose/grpc,jboeuf/grpc,firebase/grpc,chrisdunelm/grpc,mehrdada/grpc,thinkerou/grpc,muxi/grpc,pszemus/grpc,jtattermusch/grpc,nicolasnoble/grpc,simonkuang/grpc,vjpai/grpc,jtattermusch/grpc,kpayson64/grpc,geffzhang/grpc,mehrdada/grpc,donnadionne/grpc,chrisdunelm/grpc,deepaklukose/grpc,jtattermusch/grpc,ncteisen/grpc,ejona86/grpc,nicolasnoble/grpc,carl-mastrangelo/grpc,fuchsia-mirror/third_party-grpc,fuchsia-mirror/third_party-grpc,vjpai/grpc,grpc/grpc,donnadionne/grpc,vjpai/grpc,jboeuf/grpc,kpayson64/grpc,nicolasnoble/grpc,vjpai/grpc,pszemus/grpc,carl-mastrangelo/grpc,PeterFaiman/ruby-grpc-minimal,Vizerai/grpc,nicolasnoble/grpc,firebase/grpc,deepaklukose/grpc,simonkuang/grpc,stanley-cheung/grpc,ejona86/grpc,murgatroid99/grpc,fuchsia-mirror/third_party-grpc,kpayson64/grpc,ejona86/grpc,sreecha/grpc,PeterFaiman/ruby-grpc-minimal,carl-mastrangelo/grpc,carl-mastrangelo/grpc,ctiller/grpc,ctiller/grpc,jboeuf/grpc,vjpai/grpc,PeterFaiman/ruby-grpc-minimal,firebase/grpc,pszemus/grpc,deepaklukose/grpc,PeterFaiman/ruby-grpc-minimal,murgatroid99/grpc,ncteisen/grpc,muxi/grpc,PeterFaiman/ruby-grpc-minimal,grpc/grpc,dgquintas/grpc,donnadionne/grpc