$Id$ Wrapper functions for regcomp, regexec, regfree, and regerror using shared memory allocators instead of libc malloc/realloc/free. The original functions are prefixed with "shm_". The regular expression compiled with shm_regcomp() can be used with shm_regexec() simultaneously by multiple processes without locking, because regexec has its own internal locks. It can be later on freed with shm_regfree() when the expression is no longer used. Note however that 1) shm_regexec allocates shared memory for the pattern buffer when it is successfully called for the first time. 2) shm_regexec temporary allocates and deallocates memory for storing the registers for the pmatch array runtime if nmatch and pmatch parameters are not 0. This is done also in shared memory, therefore use the shared memory wrappers for regular expression based search-and-replace only if really necessary. See 'man regex' for the usage and parameters of the functions. Supported only with GNU C library.