REG_EIP is already defined elsewhere for Linux.
Can potentially send upstream.

diff --git a/js/src/asmjs/AsmJSSignalHandlers.cpp b/js/src/asmjs/AsmJSSignalHandlers.cpp
--- a/js/src/asmjs/AsmJSSignalHandlers.cpp
+++ b/js/src/asmjs/AsmJSSignalHandlers.cpp
@@ -116,6 +116,9 @@
 # define R14_sig(p) ((p)->sc_r14)
 # define R15_sig(p) ((p)->sc_r15)
 #elif defined(__linux__) || defined(SOLARIS)
+# if defined(SOLARIS)
+#  define REG_EIP EIP
+# endif 
 # if defined(__linux__)
 #  define XMM_sig(p,i) ((p)->uc_mcontext.fpregs->_xmm[i])
 #  define EIP_sig(p) ((p)->uc_mcontext.gregs[REG_EIP])